Monolithic combustor bodies

ABSTRACT

A monolithic combustor body may provide multi-stage combustion. A combustor body may include a combustion chamber body and a plurality of heating walls that include a heat sink. The combustion chamber body may be disposed annularly about a longitudinal axis and defining a combustion chamber. The plurality of heating walls may include heat sink. The plurality of heating walls may occupy a radially or concentrically outward position relative to the combustion chamber and may define a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber. During operation, the combustor body may exhibit multi-stage combustion that includes a first combustion zone occupying a distal or medial position of the combustion chamber relative to the longitudinal axis, and a second combustion zone occupying a proximal position relative to the first combustion zone and a radially or concentrically outward position of the combustion chamber and/or a radially or concentrically inward position of the plurality of combustion-gas pathways.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to each of the following U.S. Provisional Applications, the contents of which are incorporated herein by reference in their entirety for all purposes as if set forth verbatim: App. No. 62/850,599, filed May 21, 2019; App. No. 62/850,623, filed May 21, 2019; App. No. 62/850,678, filed May 21, 2019; App. No. 62/850,692, filed May 21, 2019; and App. No. 62/850,701, filed May 21, 2019. The present application also incorporates by reference International Patent Application Number PCT/US2020/033674 filed on May 20, 2020 in its entirety for all purposes.

FIELD

The present subject matter relates generally to energy conversion systems, power generation systems, and energy distribution systems. The present subject matter additionally relates to heat exchangers and heat exchanger systems. The present subject matter further relates to piston engine assemblies, such as closed-cycle engine systems. The present subject matter still further relates to systems and methods for control or operation of one or more systems of the present subject matter herein.

BACKGROUND

Power generation and distribution systems are challenged to provide improved power generation efficiency and/or lowered emissions. Furthermore, power generation and distribution systems are challenged to provide improved power output with lower transmission losses. Certain power generation and distribution systems are further challenged to improve sizing, portability, or power density generally while improving power generation efficiency, power output, and emissions.

Certain engine system arrangements, such as closed cycle engines, may offer some improved efficiency over other engine system arrangements. However, closed cycle engine arrangements, such as Stirling engines, are challenged to provide relatively larger power output or power density, or improved efficiency, relative to other engine arrangements. Closed cycle engines may suffer due to inefficient combustion, inefficient heat exchangers, inefficient mass transfer, heat losses to the environment, non-ideal behavior of the working fluid(s), imperfect seals, friction, pumping losses, and/or other inefficiencies and imperfections. As such, there is a need for improved closed cycle engines and system arrangements that may provide improved power output, improved power density, or further improved efficiency. Additionally, there is a need for an improved closed cycle engine that may be provided to improve power generation and power distribution systems.

Additionally, or alternatively, there is a general need for improved heat transfer devices, such as for heat engines, or as may be applied to power generation systems, distribution systems, propulsion systems, vehicle systems, or industrial or residential facilities. Furthermore, there is a need for improved control system and methods for operating power generation systems as may include subsystems that collectively may provide improved power generation efficiency or reduced emissions.

BRIEF DESCRIPTION

Aspects and advantages will be set forth in part in the following description, or may be apparent from the description, or may be learned through practicing the presently disclosed subject matter.

In one aspect, the present disclosure embraces monolithic combustor bodies. A monolithic combustor body may provide multi-stage combustion. A combustor body may include a combustion chamber body and a plurality of heating walls that include a heat sink. The combustion chamber body may be disposed annularly about a longitudinal axis and defining a combustion chamber. The plurality of heating walls may include heat sink. The plurality of heating walls may occupy a radially or concentrically outward position relative to the combustion chamber and may define a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber. During operation, the combustor body may exhibit multi-stage combustion that includes a first combustion zone occupying a distal or medial position of the combustion chamber relative to the longitudinal axis, and a second combustion zone occupying a proximal position relative to the first combustion zone and a radially or concentrically outward position of the combustion chamber and/or a radially or concentrically inward position of the plurality of combustion-gas pathways.

These and other features, aspects and advantages will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments and, together with the description, serve to explain certain principles of the presently disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure including the best mode, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 schematically depicts a cross-sectional view of an exemplary closed-cycle engine, which may be a regenerative heat engine and/or a Stirling engine;

FIG. 2A schematically depicts an exemplary heater body that may be included in the closed-cycle engine shown in FIG. 1;

FIG. 2B schematically depicts a cross-sectional perspective view of an exemplary heater body that may be included in the closed-cycle engine shown in FIG. 1;

FIG. 3 shows a flowchart depicting an exemplary method of heating a closed-cycle engine, such as a regenerative heat engine;

FIG. 4 schematically depicts another exemplary monolithic heater body;

FIG. 5 schematically depicts a cross-sectional view of a portion of an exemplary heater body, illustrating portions of an exemplary piston body and an exemplary heat-capture pathway;

FIG. 6A shows a cross-sectional perspective view of an exemplary combustor body portion of a heater body that may be included in the heater body shown in FIG. 2B;

FIG. 6B shows a cross-sectional perspective view of another exemplary combustor body portion of a heater body that may be included in the heater body shown in FIG. 2B;

FIG. 7A schematically depicts a cross-sectional view of an perspective exemplary heater body that includes multi-stage combustion;

FIG. 7B schematically depicts a cross-sectional top-view of an exemplary combustion zone occupying a radially-inward portion of a hot-side heat exchanger;

FIG. 8A schematically depicts a cross-sectional view of an exemplary combustor body that includes a venturi;

FIGS. 8B and 8C illustrate exemplary fluid velocity profiles for the combustor body shown in FIG. 8A;

FIGS. 9A-9E schematically depict exemplary combustor vanes;

FIG. 10A shows a flowchart depicting an exemplary method of combusting a fuel;

FIG. 10B shows a flowchart depicting another exemplary method of combusting a fuel;

FIG. 11 schematically depicts a cross sectional view of an exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 12 schematically depicts a cutaway cross sectional view of a portion of the exemplary fuel injector assembly of FIG. 11;

FIG. 13 schematically depicts a cutaway cross sectional view of a portion of the exemplary fuel injector assembly of FIG. 11;

FIG. 14 schematically depicts a cutaway cross sectional view of a portion of the exemplary fuel injector assembly of FIG. 11;

FIG. 15 schematically depicts a cutaway cross sectional view of a portion of the exemplary fuel injector assembly of FIG. 11;

FIG. 16 schematically depicts a perspective view of the fuel injector assembly of FIG. 11, viewed upstream from a downstream end;

FIG. 17 schematically depicts a perspective view of the fuel injector assembly of FIG. 1, viewed downstream from an upstream end;

FIG. 18 schematically depicts a cross sectional view of an exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 19 schematically depicts a perspective view of the fuel injector assembly of FIG. 18, viewed upstream from a downstream end;

FIG. 20 schematically depicts a schematic cross sectional view of another embodiment of the fuel injector assembly according to an aspect of the present disclosure;

FIG. 21 schematically depicts a cross sectional view of an exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 22 schematically depicts a cross sectional view of another exemplary fuel injector assembly according to an aspect of the present disclosure;

FIGS. 23 and 24 schematically depict cross sectional end-views of exemplary fuel injector assemblies according to an aspect of the present disclosure;

FIG. 25 schematically depicts a cross sectional view of another exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 26 schematically depicts a cross sectional view of another exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 27 schematically depicts a cross sectional view of another exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 28 schematically depicts a cross sectional end-view of an exemplary fuel injector assembly according to an aspect of the present disclosure;

FIG. 29 shows a top cross-sectional view of an exemplary heat exchanger body, with a plurality of heat transfer regions indicated;

FIGS. 30A and 30B show top cross-sectional views of additional exemplary embodiments of a heat exchanger body;

FIG. 31 shows a flowchart depicting an exemplary method of heating a plurality of heat transfer regions; and

FIG. 32 provides an example computing system in accordance with an example embodiment of the present disclosure.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure and not limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope of the disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. In another instance, ranges, ratios, or limits associated herein may be altered to provide further embodiments, and all such embodiments are within the scope of the present disclosure. Unless otherwise specified, in various embodiments in which a unit is provided relative to a ratio, range, or limit, units may be altered, and/or subsequently, ranges, ratios, or limits associated thereto are within the scope of the present disclosure. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

It is understood that terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. It is also understood that terms such as “top”, “bottom”, “outward”, “inward”, and the like are words of convenience and are not to be construed as limiting terms. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “substantially,” and “approximately,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 10 percent margin.

Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

The heat transfer relationships described herein may include thermal communication by conduction and/or convection. A heat transfer relationship may include a thermally conductive relationship that provides heat transfer through conduction (e.g., heat diffusion) between solid bodies and/or between a solid body and a fluid. Additionally, or in the alternative, a heat transfer relationship may include a thermally convective relationship that provides heat transfer through convection (e.g., heat transfer by bulk fluid flow) between a fluid and a solid body. It will be appreciated that convection generally includes a combination of a conduction (e.g., heat diffusion) and advection (e.g., heat transfer by bulk fluid flow). As used herein, reference to a thermally conductive relationship may include conduction and/or convection; whereas reference to a thermally convective relationship includes at least some convection.

A thermally conductive relationship may include thermal communication by conduction between a first solid body and a second solid body, between a first fluid and a first solid body, between the first solid body and a second fluid, and/or between the second solid body and a second fluid. For example, such conduction may provide heat transfer from a first fluid to a first solid body and/or from the first solid body to a second fluid. Additionally, or in the alternative, such conduction may provide heat transfer from a first fluid to a first solid body and/or through a first solid body (e.g., from one surface to another) and/or from the first solid body to a second solid body and/or through a second solid body (e.g., from one surface to another) and/or from the second solid body to a second fluid.

A thermally convective relationship may include thermal communication by convection (e.g., heat transfer by bulk fluid flow) between a first fluid and a first solid body, between the first solid body and a second fluid, and/or between a second solid body and a second fluid. For example, such convection may provide heat transfer from a first fluid to a first solid body and/or from the first solid body to a second fluid. Additionally, or in the alternative, such convection may provide heat transfer from a second solid body to a second fluid.

It will be appreciated that the terms “clockwise” and “counter-clockwise” are terms of convenience and are not to be limiting. Generally, the terms “clock-wise” and “counter-clockwise” have their ordinary meaning, and unless otherwise indicated refer to a direction with reference to a top-down or upright view. Clockwise and counter-clockwise elements may be interchanged without departing from the scope of the present disclosure.

As used herein, the terms “additively manufactured” or “additive manufacturing techniques or processes” refer generally to manufacturing processes wherein successive layers of material(s) are provided on each other to “build-up,” layer-by-layer, a three-dimensional component. The successive layers generally fuse together to form a monolithic component which may have a variety of integral sub-components.

Although additive manufacturing technology is described herein as providing fabrication of complex objects by building objects point-by-point, layer-by-layer, typically in a vertical direction, other methods of fabrication are possible and are within the scope of the present subject matter. For example, although the discussion herein refers to the addition of material to form successive layers, one skilled in the art will appreciate that the methods and structures disclosed herein may be practiced with any additive manufacturing technique or manufacturing technology. For example, embodiments of the present disclosure may use layer-additive processes, layer-subtractive processes, or hybrid processes. As another example, embodiments of the present disclosure may include selectively depositing a binder material to chemically bind portions of the layers of powder together to form a green body article. After curing, the green body article may be pre-sintered to form a brown body article having substantially all of the binder removed, and fully sintered to form a consolidated article.

Suitable additive manufacturing techniques in accordance with the present disclosure include, for example, Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), 3D printing such as by inkjets and laserjets, Sterolithography (SLA), Direct Laser Sintering (DLS), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM), Direct Metal Deposition (DMD), Digital Light Processing (DLP), Direct Laser Melting (DLM), Direct Selective Laser Melting (DSLM), Selective Laser Melting (SLM), Direct Metal Laser Melting (DMLM), Binder Jetting (BJ), and other known processes.

The additive manufacturing processes described herein may be used for forming components using any suitable material. For example, the material may be plastic, metal, concrete, ceramic, polymer, epoxy, photopolymer resin, or any other suitable material that may be in solid, liquid, powder, sheet material, wire, or any other suitable form or combinations thereof. More specifically, according to exemplary embodiments of the present subject matter, the additively manufactured components described herein may be formed in part, in whole, or in some combination of materials including but not limited to pure metals, nickel alloys, chrome alloys, titanium, titanium alloys, magnesium, magnesium alloys, aluminum, aluminum alloys, and nickel or cobalt based superalloys (e.g., those available under the name Inconel® available from Special Metals Corporation). These materials are examples of materials suitable for use in the additive manufacturing processes described herein, and may be generally referred to as “additive materials.”

In addition, one skilled in the art will appreciate that a variety of materials and methods for bonding those materials may be used and are contemplated as within the scope of the present disclosure. As used herein, references to “fusing” or “binding” may refer to any suitable process for creating a bonded layer of any of the above materials. For example, if an object is made from polymer, fusing may refer to creating a thermoset bond between polymer materials. If the object is epoxy, the bond may be formed by a crosslinking process. If the material is ceramic, the bond may be formed by a sintering process. If the material is powdered metal, the bond may be formed by a melting or sintering process, or additionally with a binder process. One skilled in the art will appreciate that other methods of fusing materials to make a component by additive manufacturing are possible, and the presently disclosed subject matter may be practiced with those methods.

In addition, the additive manufacturing process disclosed herein allows a single component to be formed from multiple materials. Thus, the components described herein may be formed from any suitable mixtures of the above materials. For example, a component may include multiple layers, segments, or parts that are formed using different materials, processes, and/or on different additive manufacturing machines. In this manner, components may be constructed which have different materials and material properties for meeting the demands of any particular application. In addition, although the components described herein are constructed entirely by additive manufacturing processes, it should be appreciated that in alternate embodiments, all or a portion of these components may be formed via casting, machining, and/or any other suitable manufacturing process. Indeed, any suitable combination of materials and manufacturing methods may be used to form these components.

An exemplary additive manufacturing process will now be described. Additive manufacturing processes fabricate components using three-dimensional (3D) information, for example a three-dimensional computer model, of the component. Accordingly, a three-dimensional design model of the component may be defined prior to manufacturing. In this regard, a model or prototype of the component may be scanned to determine the three-dimensional information of the component. As another example, a model of the component may be constructed using a suitable computer aided design (CAD) program to define the three-dimensional design model of the component.

The design model may include 3D numeric coordinates of the entire configuration of the component including both external and internal surfaces of the component. For example, the design model may define the body, the surface, and/or internal passageways such as openings, support structures, etc. In one exemplary embodiment, the three-dimensional design model is converted into a plurality of slices or segments, e.g., along a central (e.g., vertical) axis of the component or any other suitable axis. Each slice may define a thin cross section of the component for a predetermined height of the slice. The plurality of successive cross-sectional slices together form the 3D component. The component is then “built-up” slice-by-slice, or layer-by-layer, until finished.

In this manner, the components described herein may be fabricated using the additive process, or more specifically each layer is successively formed, e.g., by fusing or polymerizing a plastic using laser energy or heat or by sintering or melting metal powder. For example, a particular type of additive manufacturing process may use an energy beam, for example, an electron beam or electromagnetic radiation such as a laser beam, to sinter or melt a powder material. Any suitable laser and laser parameters may be used, including considerations with respect to power, laser beam spot size, and scanning velocity. The build material may be formed by any suitable powder or material selected for enhanced strength, durability, and useful life, particularly at high temperatures.

Each successive layer may be, for example, between about 10 μm and 200 μm, although the thickness may be selected based on any number of parameters and may be any suitable size according to alternative embodiments. Therefore, utilizing the additive formation methods described above, the components described herein may have cross sections as thin as one thickness of an associated powder layer, e.g., 10 μm, utilized during the additive formation process.

In addition, utilizing an additive process, the surface finish and features of the components may vary as need depending on the application. For example, the surface finish may be adjusted (e.g., made smoother or rougher) by selecting appropriate laser scan parameters (e.g., laser power, scan speed, laser focal spot size, etc.) during the additive process, especially in the periphery of a cross-sectional layer which corresponds to the part surface. For example, a rougher finish may be achieved by increasing laser scan speed or decreasing the size of the melt pool formed, and a smoother finish may be achieved by decreasing laser scan speed or increasing the size of the melt pool formed. The scanning pattern and/or laser power can also be changed to change the surface finish in a selected area.

After fabrication of the component is complete, various post-processing procedures may be applied to the component. For example, post processing procedures may include removal of excess powder by, for example, blowing or vacuuming. Other post processing procedures may include a stress relief process. Additionally, thermal, mechanical, and/or chemical post processing procedures can be used to finish the part to achieve a desired strength, surface finish, a decreased porosity decreasing and/or an increased density (e.g., via hot isostatic pressing), and other component properties or features.

It should be appreciated that one skilled in the art may add or modify features shown and described herein to facilitate manufacture of the system A10 provided herein without undue experimentation. For example, build features, such as trusses, grids, build surfaces, or other supporting features, or material or fluid ingress or egress ports, may be added or modified from the present geometries to facilitate manufacture of embodiments of the system A10 based at least on a desired manufacturing process or a desired particular additive manufacturing process.

Notably, in exemplary embodiments, several features of the components described herein were previously not possible due to manufacturing restraints. However, the present inventors have advantageously utilized current advances in additive manufacturing techniques to develop exemplary embodiments of such components generally in accordance with the present disclosure. While certain embodiments of the present disclosure may not be limited to the use of additive manufacturing to form these components generally, additive manufacturing does provide a variety of manufacturing advantages, including ease of manufacturing, reduced cost, greater accuracy, etc.

In this regard, utilizing additive manufacturing methods, even multi-part components may be formed as a single piece of continuous metal, and may thus include fewer sub-components and/or joints compared to prior designs. The integral formation of these multi-part components through additive manufacturing may advantageously improve the overall assembly process, reduce potential leakage, reduce thermodynamic losses, improve thermal energy transfer, or provide higher power densities. For example, the integral formation reduces the number of separate parts that must be assembled, thus reducing associated time, overall assembly costs, reduces potential leakage pathways, or reduces potential thermodynamic losses. Additionally, existing issues with, for example, leakage, may advantageously be reduced. Still further, joint quality between separate parts may be addressed or obviated by the processes described herein, such as to desirably reduce leakage, assembly, and improve overall performance.

Also, the additive manufacturing methods described above provide much more complex and intricate shapes and contours of the components described herein to be formed with a very high level of precision. For example, such components may include thin additively manufactured layers, cross sectional features, and component contours. As another example, additive manufacturing may provide heat exchanger surface areas, volumes, passages, conduits, or other features that may desirably improve heat exchanger efficiency or performance, or overall engine or system performance. In addition, the additive manufacturing process provides the manufacture of a single component having different materials such that different portions of the component may exhibit different performance characteristics. The successive, additive steps of the manufacturing process provide the construction of these novel features. As a result, the components described herein may exhibit improved functionality and reliability.

An exemplary engine c002 is shown in FIG. 1. The engine c002 may be a closed cycle engine, such as a regenerative heat engine and/or a Stirling engine; however other engines including other closed-cycle engines and/or regenerative heat engines are also contemplated and the scope of the present disclosure embraces any engine. A closed-cycle engine c002 may include a heater body c100 and an engine body c050. In the embodiment shown, a closed-cycle engine c002 may include an engine body c050 and a heater body c100 disposed on opposite sides of the engine body c050. For example, a first heater body c100 may be disposed at a first side of an engine body c050 and a second heater body c100 may be disposed at a second side of an engine body c050. In still other embodiments, a plurality of engine bodies c050 may be provided and/or a single heater body c100 or a multitude of heater bodies c100 may be provided. The closed-cycle engine c002 may include a piston assembly c090 and a load device c092 operably inserted within an engine body c050 and/or a heater body c100.

The closed-cycle engine c002 may be provided in the form of an engine assembly that includes one or more monolithic bodies or monolithic body-segments as described herein. A monolithic body and/or a monolithic body-segment may be fabricated using an additive manufacturing technology and may be void of any seams, joints, or the like characteristic of separately fabricated components. By way of example, an exemplary closed-cycle engine c002 may be assembled from an engine assembly that includes a first heater body c100 and a first engine body c050. The first heater body may define a first portion of a first monolithic body or a first monolithic body-segment, and the first engine body may define a second portion of the first monolithic body or a second monolithic body-segment operably coupled or operably couplable to the first heater body.

Now turning to FIGS. 2A and 2B, exemplary heater bodies c100 will be described. The presently disclosed heater bodies c100 may be used to supply heat to a closed-cycle engine c002 such as a regenerative heat engine and/or a Stirling engine. However, it will be appreciated that the presently disclosed heater bodies c100 may be used as a heating source in a number of other settings, all of which are within the scope of the present disclosure. In some embodiments, at least a portion of the heater body c100 may define at least a portion of a closed-cycle engine c002, such as a monolithic body or a monolithic body-segment of such a closed-cycle engine c002. For example, the monolithic body may be an additively manufactured monolithic body, or the monolithic body-segment may be an additively manufactured monolithic body-segment. However, in addition or as an alternative to additive manufacturing technology, it will be appreciated that the monolithic body or various monolithic body-segments of a closed-cycle engine c002 may be formed using any desired technology, all of which are within the scope of the present disclosure.

As shown, an exemplary heater body c100 may include a combustion chamber c102 and a recirculation pathway c104 configured to recirculate combustion gas through the combustion chamber c102. The recirculation pathway c104 may include a hot-side heat exchanger c106 configured to transfer heat from circulating combustion gas to a heat input source, such as a working-fluid body c108 defining a heat transfer region having a thermally conductive relationship with at least a portion of the hot-side heat exchanger c106. For example, heat from the combustion gas may be transferred to the heat transfer region via an engine-working fluid disposed within a working-fluid pathway c110. The working-fluid pathway c110 may be defined at least in part by the hot-side heat exchanger c106 and/or at least in part by the working-fluid body c108. The hot-side heat exchanger c106 may define a portion of the recirculation pathway c104. The heat transfer region may define a region having a have a thermally conductive relationship with the heating fluid pathway.

The heat transfer region defined by the working-fluid body c108 may include a solid body and/or a fluid pathway defined at least in part by the solid body. In an exemplary embodiment, the hot-side heat exchanger c106 may include a plurality of heating fluid pathways that have a heat transfer relationship with a plurality of heat transfer regions. For example, the plurality of heat transfer regions have a thermally conductive relationship with a corresponding portion of the plurality of heating fluid pathways. Additionally, or in the alternative, the heat transfer regions may have a thermally convective relationship with a heating fluid flowing through the heating fluid pathways. The heat transfer regions may be circumferentially spaced about the longitudinal axis of the heater body c100. Respective ones of the plurality of heat transfer regions may include a solid body and/or a fluid pathway defined at least in part by the solid body.

The working-fluid body c108 may include one or more portions of a closed-cycle engine c002, such as a piston chamber c112 (e.g., a hot piston chamber) and/or a regenerator body c114. A fluid pathway defined the working-fluid body c108 may fluidly communicate with the piston chamber and the regenerator body c114. The engine-working fluid disposed within the working-fluid pathway c110 may be an engine-working fluid, such as an inert gas, which may flow in an alternating fashion between the piston chamber c112 and the regenerator body c114. The hot-side heat exchanger c106 may be provided in the form of a heat exchanger body. The heat exchanger body may define a monolithic body portion of the heater body c100 or a monolithic body-segment operably coupled or operably couplable to a monolithic heater body c100 or to one or more other monolithic body-segments that make up the heater body c100.

The recirculation pathway c104 may additionally include a recirculation eductor c116 configured to utilize intake air flowing through an intake air pathway c118 to entrain and/or accelerate combustion gas and thereby provide a mixture of intake air and recirculating combustion gas to the combustion chamber c102. The recirculation eductor c116 may also include an exhaust pathway c120 configured to discharge a portion of the combustion gas as exhaust gas. The recirculation eductor c116 may fluidly communicate with a downstream portion of the hot-side heat exchanger c106. The recirculation eductor c116 may be provided in the form of an eductor body. The eductor body may define a monolithic body portion of the heater body c100 or a monolithic body-segment operably coupled or operably couplable to a monolithic heater body c100 or to one or more other monolithic body-segments that make up the heater body c100.

In some embodiments, the heater body c100 may include a conditioning conduit c122 fluidly communicating with a downstream portion of the recirculation eductor c116 and an upstream portion of the combustion chamber c102. The conditioning conduct c122 may be configured to guide combustion gas (e.g., a mixture of intake air and recirculating combustion gas) to the combustion chamber c102, and may be configured with a size and shape so as to condition one or more fluid dynamic properties of the combustion gas flowing to the combustion chamber c122. Exemplary fluid dynamics properties that may be conditioned by the conditioning conduit c122 include pressure, pressure gradient, flow velocity, velocity gradient, turbulence, vorticity, curl, and so forth. The conditioning conduit c122 may define a conduit volume selected to provide one or more desired fluid dynamics properties of combustion gas flowing therethrough, and/or to allow for mixing of intake air with recirculating combustion gas. In some embodiments, the conditioning conduit c122 may be configured to swirl combustion gas flowing therethrough. For example, the conditioning conduit c122 may establish or sustain a vortex, which may enhance combustion quality in the combustion chamber c102. Additionally, or in the alternative, combustion gas circulating through the conditioning conduit c122 may cool the combustion chamber c102, with heat from the combustion chamber c102 heating the combustion gas prior to entering the combustion chamber c102.

The combustion chamber c102 and the conditioning conduit c104 may be provided in the form of a combustor body. The combustor body may define a monolithic body portion of the heater body c100 or a monolithic body-segment operably coupled or operably couplable to a monolithic heater body c100 or to one or more other monolithic body-segments that make up the heater body c100.

The heater body c100 may additionally include a heat recuperator c124 configured to utilize exhaust gas flowing through the exhaust pathway c120 to preheat intake air flowing through the intake air pathway c118, thereby recuperating heat from the exhaust gas. The terms preheater and recuperator may be used interchangeably; however, in some instances, the term preheater may be used with reference to preheating intake air flowing through the intake air pathway c118, and the term recuperator may be used with reference to recuperating heat from exhaust gas flowing through the exhaust pathway c120. The heat recuperator c124 may be provided in the form of a heat recuperator body. The heat recuperator body may define a monolithic body portion of the heater body c100 or a monolithic body-segment operably coupled or operably couplable to a monolithic heater body c100 or to one or more other monolithic body-segments that make up the heater body c100. As shown in FIG. 2A, the heat recuperator c124 may be located downstream from the recirculation eductor c116 relative to the exhaust gas pathway c120 and upstream from the recirculation eductor c116 relative to the intake air pathway c118. The heat recuperator located as shown in FIG. 2A may exchange heat between exhaust gas flowing through the exhaust gas pathway c120 and intake air flowing through the intake air pathway c118.

One or more fuel nozzles c126 may be operably coupled to the heater body c100. Fuel may be supplied to the combustion chamber c102 by one or more fuel lines c103. For example, the one or more fuel nozzles c126 may be operably coupled to the combustion chamber c102. Fuel injected into the combustion chamber c102 may combine with circulating combustion gas to provide a suitable air-to-fuel ratio. The fuel and at least a portion of the circulating combustion gas may be combusted in the combustion chamber so as to generate hot combustion gas. The combustion chamber c102 may fluidly communicate with an upstream portion of the hot-side heat exchanger c106, thereby suppling the hot combustion gas to the hot-side heat exchanger c106 for heating the working-fluid body c108. One or more intake air pathways c118, one or more exhaust gas pathways c120, one or more recirculation pathways c104, and one or more fuel lines c103 may collectively define a primary flowpath c121.

FIG. 2B schematically depicts a cross-sectional perspective view of an exemplary heater body c100. As shown, an exemplary heater body c100 may have an annular configuration, however, other configurations are also contemplated. The heater body c100 may include a plurality of monolithic body portions that together may define a monolithic heater body c100. Alternatively, or in addition, the heater body c106 may include one or more monolithic body-segments operably coupled or operably couplable to a monolithic heater body c100. Further, a plurality of monolithic body-segments may be operably coupled or operably couplable to one another to define at least a portion of a heater body c100. In an exemplary embodiment, a heater body c100 may define a single monolithic body. In other embodiments, a plurality of monolithic body-segments may be operably coupled to one another, such as via welding, fusing, or the like, so as to provide an integrally formed heater body c100.

A heater body c100 and/or various featured thereof may include a proximal portion c200 and a distal portion c202 oriented relative to a longitudinal axis c204, with a medial portion c206 disposed between the proximal portion c200 and the distal portion c202. The proximal portion c200 of the heater body c100 or a feature thereof refers to a portion, relative to a longitudinal axis c204, adjacent or relatively proximate to a working-fluid body c108 such as one or more pistons of a closed-cycle engine c002. The distal portion c202 of the heater body c100 or a feature thereof refers to a portion, relative to the longitudinal axis c204, opposite from or relatively remote to the working-fluid body c108. A proximal, distal, or medial portion c200, c202, c206 need not refer to a finite point on the heater body c100 or a feature thereof; rather, it will be appreciated that the terms proximal, distal, and medial c200, c202, c206 may be used generally, such as to denote the location of a portion of the heater body c100 or a feature thereof relative to the working-fluid body c108 and/or to denote the location of various features of the heater body c100 relative to one another.

Referring still to FIG. 2B, a heater body c100 may include a combustion chamber c102 and a hot-side heat exchanger c106 circumferentially surrounding at least a portion of the combustion chamber c102. In some embodiments, a recirculation pathway c104 may circumferentially surround at least a portion of the combustion chamber c102. A heater body c100 may additionally or alternatively include a conditioning conduit c122 circumferentially surrounding at least a portion of the combustion chamber c102. For example, as shown, the hot-side heat exchanger c106 may circumferentially surround a proximal portion c200 of the combustion chamber c102 and the conditioning conduit c122 may circumferentially surround a medial portion c206 and/or a distal portion c202 of the combustion chamber c102. In some embodiments, the hot-side heat exchanger c106 may additionally circumferentially surround at least some of a medial portion c206 of the combustion chamber c102. In some embodiments, it may be advantageous for the combustion chamber c102 to be aligned with the longitudinal axis c204 and/or for a plurality of combustion chambers c102 to be circumferentially spaced (e.g., evenly distributed) about the longitudinal axis c204. For example, such alignment and/or even distribution may encourage relatively even heat distribution within the heater body c100 and/or the hot-side heat exchanger c106. Such relatively even heat distribution may, in turn, encourage relatively even heat transfer from the hot-side heat exchanger c106 (e.g., from a heating fluid flowing therethrough) to the plurality of heat transfer regions.

The heater body c100 may further include a recirculation eductor c116 circumferentially surrounding the combustion chamber c102. When the heater body c100 includes a conditioning conduit c122, the recirculation eductor c116 may be disposed radially or concentrically outward from the conditioning conduit c122, for example, such that the recirculation eductor c116 circumferentially surrounds at least a portion of the conditioning conduit c122. For example, the recirculation eductor c116 may circumferentially surround a distal portion c202 and/or a medial portion (e.g., a distally-medial portion) of the combustion chamber c102. Additionally, when the heater body c100 includes a conditioning conduit c122, the recirculation eductor c116 may circumferentially surround a distal portion c202 and/or a medial portion (e.g., a distally-medial portion) of the conditioning conduit c122. The recirculation eductor c116 may be disposed axially adjacent to the hot-side heat exchanger c106, such as adjacent to a distal portion c202 of the hot-side heat exchanger c106 relative to the longitudinal axis c204.

In some embodiments, a heater body c100 may include a heat recuperator c124 circumferentially surrounding the combustion chamber c102. When the heater body c100 includes a conditioning conduit c122, the heat recuperator c124 may be disposed radially or concentrically outward from the conditioning conduit c122, for example, such that the heat recuperator c124 circumferentially surrounds at least a portion of the conditioning conduit c122. For example, the heat recuperator c124 may circumferentially surround a distal portion c202 and/or a medial portion (e.g., a distally-medial portion) of the combustion chamber c102. Additionally, when the heater body c100 includes a conditioning conduit c122, the heat recuperator c124 may circumferentially surround a distal portion c202 and/or a medial portion (e.g., a distally-medial portion) of the conditioning conduit c122. The heat recuperator c124 may be disposed axially adjacent to the recirculation eductor c116, such as adjacent to a distal portion c202 of the recirculation eductor c116 relative to the longitudinal axis c204.

In some embodiments, as shown for example in FIG. 2B, a heater body c100 may include a heat shield c127. The heat shield c127 may be configured to insulate and/or shield one or more portions of the heater body c100 from a heat source within the heater body c100. For example, the heat source may include a combustion flame and/or combustion gas circulating through the recirculation pathway c104, and/or portions of the heater body c100 that become heated by the combustion flame and/or combustion gas. Additionally, or in the alternative, the heat shield c127 may provide a heat sink to absorb and/or dissipate heat, such as heat from a combustion flame and/or combustion gas circulating through the recirculation pathway c104. In some embodiments, the heat shield c127 may include a cooling jacket c128 defined by an inner wall c130 and an outer wall c132. The cooling jacket c128 may fluidly communicate with the intake air annulus c216, such that intake air may flow therethrough. Additionally, or in the alternative, the cooling jacket c128 may define a space with a vacuum or near vacuum. The cooling jacket c128 may define one or more pathways, such as an annular pathway or a plurality of semi-annular pathways. The cooling jacket may cool hot portions of the heater body c100, for example to maintain suitable operating temperatures and/or to shield users or surrounding equipment from hot portions of the heater body c100.

A heater body c100 may define a single monolithic body providing a recirculation pathway c104, an intake air pathway c118, and/or an exhaust pathway c120. For example, a plurality of monolithic body portions may together define a single monolithic body. Alternatively, a heater body c100 may include separate monolithic body-segments respectively defining a recirculation pathway c104, an intake air pathway c118, and/or an exhaust pathway c120. In some embodiments, a first monolithic body-segment may define a recirculation pathway c104, a second monolithic body-segment may define an intake air pathway c118, and a third monolithic body-segment may define an exhaust pathway c120. Such monolithic body-segments may be coupled to one another, such as via welding, fusing, or the like, so as to provide an integrally formed heater body c100.

A monolithic body defining a recirculation pathway c104 may include a combustion chamber c102 and a hot-side heat exchanger c106 fluidly communicating with a proximal portion c200 of the combustion chamber c102. Such a monolithic recirculation pathway c104 may additionally include a recirculation eductor c116 fluidly communicating with a radially or concentrically outward portion of the hot-side heat exchanger c106 and a conditioning conduit c122 having a proximal portion c200 fluidly communicating with a radially or concentrically inward portion of the recirculation eductor c116 and a distal portion c202 fluidly communicating with a distal portion c202 of the combustion chamber c102.

In some embodiments, a heater body c100 may include a recirculation annulus c208. The recirculation annulus c208 may be disposed radially or concentrically outward from at least a portion of the hot-side heat exchanger c106 and/or at least a portion of the recirculation eductor c116. Additionally, or in the alternative, the recirculation annulus c208 may circumferentially surround at least a portion of the hot-side heat exchanger c106 and/or at least a portion of the recirculation eductor c116. The recirculation annulus c208 may fluidly communicate with a radially or concentrically outward portion of the hot-side heat exchanger c106 and a radially or concentrically outward portion of the recirculation eductor c116 so as to define a pathway to direct at least a portion of the combustion gas discharging from the hot-side heat exchanger c106 into the recirculation annulus c208.

In some embodiments, a heater body c100 may include fuel injector body c401. The fuel injector body c401 may include a combustor cap c210 providing fluid communication between a distal portion c202 of the conditioning conduit c122 and a distal portion c202 of the combustion chamber c102. The fuel injector body c401 may additionally or alternatively include one or more fuel nozzles c214. The fuel injector body c401 and/or the combustor cap c210 and/or one or more fuel nozzles c214 may be a separate component operably coupled or operably couplable to the heater body c110, such as at a distal portion c202 of the conditioning conduit c122 as shown. Additionally, or in the alternative, the fuel injector body c401 and/or the combustor cap c210 and/or one or more fuel nozzles c214 may be a portion of a monolithic body defining at least a portion of the heater body c100.

In some embodiments, one or more fuel nozzles c214 may be operably coupled to the combustor cap c210. For example, the combustor cap c210 may include one or more nozzle ports c212 respectively configured to receive a fuel nozzle c214. One or more fuel nozzles c214 may be operably coupled to corresponding nozzle ports c212 such as by mating threads or the like. The one or more fuel nozzles c214 may include a glow plug c215 operable to ignite fuel and/or combustion gas in the combustion chamber c102. As shown, the fuel nozzle may be aligned with the longitudinal axis c204 of the heater body c100 and may be concentric with the combustion chamber c102. Additionally, or in the alternative, one or more fuel nozzles c214 may be circumferentially spaced about the distal portion c202 of the combustion chamber. In some embodiments, it may be advantageous for a fuel nozzle c214 to be aligned with the longitudinal axis c204 and/or for a plurality of fuel nozzles c214 to be circumferentially spaced (e.g., evenly distributed) about the longitudinal axis c204. For example, such alignment and/or even distribution may encourage flame stability within the combustion chamber c102 and/or relatively even heat distribution within the combustion chamber c102 and/or the hot-side heat exchanger c106.

A monolithic body defining an intake air pathway c118 may include an intake air body, such as an intake air annulus c216 and/or a monolithic body defining an exhaust pathway c120 may include an exhaust body, such as an exhaust annulus c218. The intake air annulus c216 and the exhaust annulus c218 may define portions of a single monolithic body or may be separate monolithic body-segments operably coupled or operably couplable to one another. The intake air annulus c216 and/or the exhaust annulus c218 may circumferentially surround at least a portion of the combustion chamber c102. As shown, the intake air annulus c216 may include one or more intake ports c220 and the exhaust annulus c218 may include one or more exhaust ports c222. As shown in FIG. 2B, the intake air annulus c216 and the exhaust annulus c218 may be disposed axially adjacent to one another. For example, the intake air annulus c216 may be adjacent to a distal portion c202 of the exhaust annulus c218 and/or the exhaust annulus c218 may be adjacent to a proximal portion of the intake air annulus c216 relative to the longitudinal axis c204.

The intake air annulus c216 may include a plurality of intake vanes c224 circumferentially spaced about the intake air annulus c216. The intake vanes c224 may define at least a portion of a pathway configured to direct intake air from the intake air annulus c216 to the recirculation pathway c104. The exhaust annulus c218 may include a plurality of exhaust vanes c226 circumferentially spaced about the exhaust annulus c218. The exhaust vanes c226 may define at least a portion of a pathway configured to direct exhaust gas into the exhaust pathway c218.

During operation, intake air is directed into the intake air annulus c216. In some embodiments, the intake air may be pressurized, such as via a compressor (not shown), to induce a flow of intake air into the intake air pathway c118. The intake air circulates counterclockwise through the intake air annulus c216, where a plurality of intake vanes c224 circumferentially spaced about the intake air annulus c216 direct the intake air in a radially or concentrically inward and axially proximal spiral having a counterclockwise orientation. The intake air flowing through the intake vanes c224 continues a radially or concentrically inward spiral flow through the heat recuperator c124 and into the motive annulus c228. The intake air in the motive annulus c228 enters the recirculation eductor c116 through a plurality of eductor slots configured to accelerate the intake air spirally into the conditioning conduit c122. The intake air passing through the eductor slots accelerates and entrains combustion gas flowing into the recirculation eductor c116 from the recirculation annulus c208. The intake air and the combustion gas mix to provide fresh combustion gas while flowing helically through the conditioning conduit c122 in an axially distal direction. The fresh combustion gas reaches the combustion cap c210, which directs the flow of fresh combustion gas into the combustion chamber while a fuel nozzle c214 introduces a flow of fuel, which may include a liquid, gaseous fuel.

In the combustion chamber c102, fuel combines with the fresh combustion gas and is ignited, for example, by a glow plug or a spark plug. The combustion chamber c102 provides a vortex combustion pattern with a counterclockwise flow. Centripetal force of the vortex combustion pattern draw the combustion flame radially or concentrically inward while propelling unburnt combustion gas radially or concentrically outward. The combustion gas continues with a spiral counterclockwise flow out of the combustion chamber c102 and into the hot-side heat exchanger c106. The combustion gas flows in a radially or concentrically outward counterclockwise spiral through the hot-side heat exchanger c106 and into the recirculation annulus c208.

The recirculation annulus c208 directs the combustion gas in an axially distal and radially or concentrically inward direction into the recirculation eductor c116, where a portion of the combustion gas is accelerated and entrained by intake air flowing through the eductor slots of the recirculation eductor c116. The remainder of the combustion gas flows in an axially distal direction through exhaust slots in the recirculation eductor c116. The exhaust slots in the recirculation eductor c116 reverse the direction of the exhaust gas flow, directing the exhaust gas in an axially distal and clockwise spiral direction into the recuperator body portion of the heat recuperator c124. The exhaust gas flow in a clockwise spiral into the exhaust annulus c218, where the exhaust gas discharges from the heater body c100 through one or more exhaust ports c222.

Referring still to FIG. 2B, an exemplary heater body c100 may include a combustion chamber c102 and a recirculation pathway c104 configured to recirculate combustion gas through the combustion chamber c102. The heater body c100 includes an intake air pathway c118 and an exhaust pathway c120 may fluidly communicate with the recirculation pathway c104. The recirculation pathway c104 may include a hot-side heat exchanger c106 and a recirculation eductor c116. However, in some embodiments, the recirculation eductor c116 may be omitted and the combustion chamber c102 may fluidly communicate with the intake air pathway c118 and the exhaust pathway c120 with combustion gas discharging from the heater body without recirculating. The exhaust pathway c120 may fluidly communicate with the recirculation pathway c104 upstream from the intake air pathway c118.

In some embodiments, the recirculation eductor c116 may define at least a portion of the exhaust pathway c120. For example, the exhaust pathway c120 may fluidly communicate with the recirculation pathway c104 at the recirculation eductor c116, such that the exhaust pathway c120 discharges a portion of the combustion gas from the recirculation eductor c116 as exhaust gas.

When the heater body c100 includes a recirculation pathway c104, the proportion of combustion gas may be recirculated may vary depending on the operating conditions of the heater body c100. The proportion of combustion gas may be recirculated to the proportion of fresh intake air may be utilized may be described by a recirculation ratio R, according to the following equation (1): R=I/C, where I is the flow rate if intake air flowing into the heater body c100 and T is C the flow rate of combustion gas flowing to the combustion chamber. The recirculation ratio may vary from 0% to 100% depending, for example, on the operating conditions of the heater body c100. For example, a greater proportion of intake air may be utilized during startup, with recirculation ratio increasing as the heater body c100 transitions from startup conditions to steady-state conditions. Additionally, the recirculation ratio may depend on desired combustion conditions, such as equivalence ratio. In some embodiments, the recirculation ratio may be from 0% to 90%, such as from 10% to 90%, such as from 0% to 60%, such as from about 30% to about 70%, such as from 40% to 60%. During startup conditions, the recirculation ratio may be from 0% to 50%, such as from 0% to 30% or from 0% to 10%. During steady-state conditions, the recirculation ratio may be from 10% to 90%, such as from 10% to 60%, or from 30% to 60%. The remainder of combustion gas may be discharged from the recirculation pathway c104 as exhaust gas.

Now referring to FIG. 3 exemplary methods of heating a heat exchanger body c600 will be described. The exemplary methods of heating a heat exchanger body c600 may include, for example, methods of heating a closed-cycle engine c002. For example, exemplary methods may be performed in connection with operation of a heater body c100 and/or a closed-cycle engine c002 as described herein. As shown in FIG. 3, an exemplary method c150 may include, at block c152, circulating combustion gas through a combustion chamber c102 and a recirculation pathway c104 configured to recirculate combustion gas through the combustion chamber c102. The recirculation pathway c104 may include a hot-side heat exchanger c106 and a recirculation eductor c116. The hot-side heat exchanger c106 may fluidly communicate with a proximal portion of the combustion chamber c102. The recirculation eductor c116 may fluidly communicate with a downstream portion of the hot-side heat exchanger c106 and a proximal portion of the conditioning conduit c122 and/or and a distal portion of the combustion chamber c102. At block c154, an exemplary method c150 may include transferring heat from the combustion gas in the hot-side heat exchanger c106 to a plurality of heat transfer regions that respectively have a heat transfer relationship with a corresponding semiannular portion of the hot-side heat exchanger c106. The exemplary method c150 may include, at block c156, swirling combustion gas through a conditioning conduit c122 defining at least a portion of the recirculation pathway c104. The conditioning conduit c122 may fluidly communicate with a downstream portion of the recirculation eductor c116 and a distal portion of the combustion chamber c102. The exemplary method c150 may additionally include, at block c158, combusting a fuel and/or at least a portion of the combustion gas. The fuel and/or combustion gas may be combusted in the combustion chamber c102. In some embodiments, at least a portion of the combustion may take place within the hot-side heat exchanger c106.

In some embodiments, an exemplary method c150 may include, at block c160, injecting intake air into the recirculation pathway c104. The intake air may be injected through an intake air pathway c118 fluidly communicating with the recirculation pathway c104. For example, a recirculation eductor c116 may include a motive pathway defining at least a portion of the intake air pathway c118. The exemplary method may additionally include, at block c162, entraining and/or accelerating combustion gas circulating through the recirculation pathway c104 at least in part by injecting the intake air into the recirculation pathway c104, for example, through the motive pathway of the recirculation eductor c116. The exemplary method may further include, at block c164, discharging a portion of the combustion gas from the recirculation pathway c104 as exhaust gas. The exhaust gas may discharge through an exhaust pathway c120, and the exhaust gas pathway c120 may fluidly communicate with the recirculation pathway c104. In some embodiments, the exhaust gas pathway c120 may be defined at least in part by the recirculation eductor c116. The exhaust gas may be preferentially discharged from the recirculation pathway c104 upstream from a location where the intake air pathway c118 fluidly communicates with the recirculation pathway c104.

The exemplary method may additionally include, at block c166, preheating intake air flowing through the intake air pathway c118. The intake air may be preheated at least in part using exhaust gas flowing through an exhaust pathway c120 by the exhaust pathway c120 having a thermally conductive relationship with the intake air pathway c118. For example, in some embodiments, the intake air may be preheated at least in part using a heat recuperator c124. The heat recuperator c124 may define at least a portion of the intake air pathway c118 and at least a portion of the exhaust pathway c120, thereby providing a thermally conductive relationship between the exhaust gas pathway c120 and the intake air pathway c118. Additionally, or in the alternative, the intake air may be preheated at least in part using combustion gas flowing through a recirculation pathway c104 by the recirculation pathway c104 having a thermally conductive relationship with the intake air pathway c118. With the heat recuperator c124 fluidly communicating with the recirculation eductor c116, the exemplary method c150 may include flowing combustion gas from the recirculation pathway c104 into the heat recuperator c124 at the recirculation eductor c116 through the exhaust pathway c120, and flowing intake air from the intake air pathway c118 into the recirculation eductor c116 at the heat recuperator c124. The exhaust pathway c120 may preferably be located upstream from the intake air pathway c118.

In an exemplary embodiment, transferring heat from the combustion gas in the hot-side heat exchanger c106 at block c154 may include transferring heat to a working-fluid body c108. The working-fluid body c108 may include a solid body and/or fluid in a fluid pathway defined at least in part by the solid body. The heat transferring to the working-fluid body c108 may come from combustion gas flowing through a plurality of heating fluid pathways defined at least in part by the hot-side heat exchanger c106. The heat may be transferred to respective ones of a plurality of heat transfer regions that have a thermally conductive relationship with a corresponding portion of the plurality of heating fluid pathways. The working-fluid body c108 may include a plurality of working-fluid pathways, and the exemplary method c150 may include flowing fluid through the working-fluid pathways as heat transfers thereto from the hot-side heat exchanger c106. In some embodiments, the working-fluid pathways may fluidly communicate with a piston chamber and a regenerator of a closed-cycle engine c002, and the exemplary method may include flowing fluid through the working-fluid pathways alternatingly between the regenerator and the piston chamber.

In an exemplary embodiment, combusting a fuel and/or at least a portion of the combustion gas at block c158 may include combusting fuel and at least a portion of the combustion gas in the combustion chamber c102 and/or in the heating fluid pathways of the hot-side heat exchanger c106. The fuel may be supplied by a fuel nozzle fluidly communicating with the combustion chamber c102. The combustion gas circulating through the combustion chamber c102 and/or the recirculation pathway c104 at block c152 may be from 10% to 90% of the total combustion gas flowing into the combustion chamber c102, and the remainder of the combustion gas may be discharged from the recirculation pathway c104 as exhaust gas through the exhaust pathway c120. It will be appreciated that the proportion of combustion gas being recirculated may vary depending on operating conditions and/or configuration of the heater body c100. For example, the proportion of combustion gas being recirculated may vary as between startup and steady-state conditions. Also, in some embodiments, the heater body c100 may not have a recirculation pathway or the recirculation pathway may be closed so as to carry out combustion of the fuel utilizing 100% intake air.

Now referring to FIGS. 4 and 5, further exemplary embodiments will be described that pertain to a heater body c100, such as a monolithic heater body c100, and/or to one or more monolithic body-segments that make up the heater body c100. A heater body c100 and/or a monolithic body-segment may include one or more features that allow the heater body c100 to operate at a relatively elevated temperature. For example, such features may include one or more heat shields c127, one or more heat-capture pathways c133, and/or one or more thermal expansion joints c135, as respectively described herein. Such features may allow for a closed cycle engine such as a Sterling engine to operate at with an improved temperature ratio (THot,engine/TCold,ambient) and/or with an improved Carnot efficiency. For example, in some embodiments, a closed cycle engine that includes a heater body c100 configured in accordance with the present disclosure may exhibit a temperature ratio of from about 2 to about 4, such as at least about 2, such as at least about 3, or such as at least about 3.5. Additionally, or in the alternative, a closed cycle engine that includes a heater body c100 configured in accordance with the present disclosure may exhibit an improved Carnot efficiency, such as a Carnot efficiency 40% to about 60%, such as from about 50% to about 70%, such as from about 60% to about 70%, such as from about 60% to about 80%; such as at least about 50%, such as at least about 60%, such as at least about 65%. Such improved temperature ratio and/or improved Carnot efficiency may be attributable at least in part to the heater body c100 being configured according to the present disclosure. By way of example, the one or more heat shields c127, the one or more heat-capture pathways c133, and/or the one or more thermal expansion joints c135, may allow the heater body c100 to operate at an elevated temperature, thereby increasing the temperature difference between a hot side and a cold side of a heat engine, and corresponding conversation of heat energy to mechanical work, effective to impart such temperature ratio and/or such Carnot efficiency.

In some embodiments, a one or more portions of a monolithic heater body c100, and/or to one or more monolithic body-segments that make up the heater body c100, may include a heat shield c127. The heat shield c127 may be configured to insulate and/or shield one or more portions of the heater body c100 from a heat source within the heater body c100. For example, the heat source may include a combustion flame and/or combustion gas circulating through the recirculation pathway c104, and/or portions of the heater body c100 that become heated by the combustion flame and/or combustion gas. Additionally, or in the alternative, the heat shield c127 may provide a heat sink to absorb and/or dissipate heat, such as heat from a combustion flame and/or combustion gas circulating through the recirculation pathway c104. FIG. 4 shows a variety of exemplary locations for a heat shield c127.

As shown, in some embodiments, a heat shield c127 may be disposed about an exterior region of a heater body c100. For example, a first heat shield c127A may circumferentially surround at least a portion of a hot-side heat exchanger c106 and/or at least a portion of a working-fluid body c108, such as an outward portion of a hot-side heat exchanger c106 and/or an outward portion of a working-fluid body c108. The first heat shield c127A may be disposed about an annular or semi-annular portion of the hot-side heat exchanger c106, and/or an annular or semi-annular portion of the working-fluid body c108.

Additionally, or in the alternative, a second heat shield c127B may be disposed about an inward portion of a heater body c100, such as an inward annular portion of a heater body c100 or an inward semi-annular portion of a heater body c100. As shown, the second heat shield c127B may be disposed about an inward annular or semiannular portion of a hot-side heat exchanger c106 and/or working-fluid body c108. The second heat shield c127B may be additionally or alternatively disposed about a radial portion of the hot-side heat exchanger c106 and/or working-fluid body c108, such as an upper radial portion (as shown) and/or a lower radial portion. The second heat shield c127B may follow a contour or profile of the hot-side heat exchanger c106 and/or working-fluid body c108. The second heat shield c127C may be disposed between the hot-side heat exchanger c106 and a recirculation eductor c116.

In addition, or in the alternative, to the first heat shield c127A and the second heat shield C127B, a heater body c100 may include a third heat shield c127C disposed about at least a portion of a combustor body c400. For example, the third heat shield c127 may circumferentially surround at least a portion of the combustion chamber c102, such as a proximal portion c200 of the combustion chamber c102.

It will be appreciated that the locations of the heat shields c127 shown in FIG. 4 are provided by way of example and are not to be limiting. In fact, a heat shield c127 may be provided at any desirable location of a heater body c100. Other exemplary location for a heat shield c127 may include an exhaust body c504, a heat recuperation body c500, a motive annulus body c506, a conditioning conduit body c404, an eductor body c300, a regenerator body c800, a piston body c700, and/or a recirculation annulus body c302.

Referring still to FIGS. 4 and 5, in some embodiments, an heater body c100 may include one or more heat-capture pathways c133. The one or more heat-capture pathways c133 may be defined by the monolithic structure of the heater body c100 and/or by the monolithic structure of one or more monolithic body segments that make up the heater body c100. A heat-capture pathway c133 may be provided at any desired location of the heater body c100. The heat-capture pathway c133 may be configured to transport a heat-capture fluid. As used herein, the term “heat-capture fluid” includes any suitable fluid transported through a heat-capture pathway c133 that, during operation of the heater body c100, has a temperature that is lower than a portion of the heater body c100 intended to be cooled by the fluid in the heat-capture pathway c133.

A heat-capture pathway c133 may capture heat from one or more regions of a heater body c100. In some embodiments, a heat-capture pathway c133 may include a flowpath configured to flow a fluid disposed within the heat-capture pathway c133 to a relatively hotter region of the heater body c100, such as from a radially or concentrically outward portion of the heater body c100 to a radially or concentrically inward portion of the heater body c100, and/or from a distal portion of the heater body c100 to a proximal portion of the heater body c100. By way of example, a heat-capture pathway c133 may include a flowpath configured to flow a fluid to the combustion chamber c102 and/or an upstream portion of a hot-side heater body c106. Additionally, or in the alternative, a heat-capture pathway c133 may cool hot portions of the heater body c100, for example to maintain suitable operating temperatures and/or to shield users or surrounding equipment from hot portions of the heater body c100.

In an exemplary embodiment, the heat-capture fluid may include a process fluid derived from a fluid pathway located elsewhere in the heater body c100, such as a fluid extracted from a primary flowpath c121 of the heater body c100. For example, the heat-capture fluid may include a process gas, such as intake air, exhaust gas, combustion gas, and/or a fuel. Such combustion gas may include a combination of intake air, fuel, uncombusted or partially combusted combustion gas c428, and/or exhaust gas. Intake air may be supplied from an intake air pathway c118 to a heat-capture pathway c133 fluidly communicating with the intake air pathway c118. Exhaust gas may be supplied from an exhaust pathway c120 to a heat-capture pathway c133 fluidly communicating with the exhaust pathway c120. Combustion gas may be supplied from a recirculation pathway c104 to a heat-capture pathway c133 fluidly communicating with the recirculation pathway c104. Fuel may be supplied from a fuel supply line to a heat-capture pathway c133 fluidly communicating with the fuel supply line.

In some embodiments, the heat-capture pathway c133 may be configured to discharge a cooling fluid to a fluid pathway located elsewhere in the heater body c100 after having been utilized to provide cooling to a location of the heater body c100. For example, a heat-capture pathway c133 may be configured to discharge a cooling fluid to a location along a primary flowpath c121 of the heater body c100, such as to an intake air pathway c118, an exhaust gas pathway c120, a recirculation pathway c104, and/or a fuel line c103. The heat-capture pathway c133 may discharge cooling fluid to a fluid pathway of the primary flowpath c121 that is the same or different from the fluid pathway of the primary flowpath c121 from which the cooling fluid is obtained. For example, a heat-capture pathway c133 that utilizes intake air for cooling may discharge to an intake air pathway c118. Additionally, or in the alternative, a heat-capture pathway c133 that utilizes intake air for cooling may discharge to an exhaust gas pathway c120, to a recirculation pathway c104, and/or to a fuel line c103. A heat-capture pathway c133 that utilizes combustion gas, fuel, and/or exhaust gas, may discharge to an intake air pathway c118, an exhaust gas pathway c120, a recirculation pathway c104, and/or a fuel line c103. In some embodiments, a heat-capture pathway c133 may include a cooling jacket c128. Additionally, or in the alternative, a heat-capture pathway c133 may fluidly communicate with a cooling jacket c128.

As used herein, the term “heat-capture pathway” includes any fluid pathway configured to capture heat from a location of the heater body c100, and/or to provide cooling to a location of the heater body c100, apart from heat transfer that occurs along the primary flowpath c121. A heat-capture pathway c133 that utilizes a fluid from the primary flowpath c121 may be differentiated from the primary flowpath c121 by the heat-capture pathway c133 having an intended purpose of capturing heat from one or more portions of the heater body c100, and/or providing cooling to one or more portions of the heater body c100, separate and apart from a respective intended purpose of the primary flowpath c121, even though portions of the primary flowpath c121 inherently provide heat capture and/or cooling with respect to portions of the heater body c100. By way of example, a heat-capture pathway c133 that utilizes fluid from the primary flowpath c121 may transects a portion of the heater body c100 that differs from that of the primary flowpath c121, thereby capturing heat from a portion of the heater body c100 located elsewhere relative to the primary flowpath c121 and/or providing cooling to a portion of the heater body c100 located elsewhere relative to the primary flowpath c121. Additionally, or in the alternative, a heat-capture pathway c133 that utilizes fluid from the primary flowpath c121 may have an inlet and an outlet that fluidly communicate with respectively different portions of the primary flowpath c121. A heat-capture pathway c133 that utilizes fluid from the primary flowpath c121 may additionally or alternatively have a heat transfer relationship with a location of the heater body c100 where, during operation of the heater body c100, at least one location of the heater body c100 has a heat transfer relationship with respect to the fluid in the heat-capture pathway c133 that includes a temperature gradient that is greater than the temperature gradient of a heat transfer relationship between such location of the heater body c100 and the primary flowpath c121. By way of contrasting illustration, the respective flowpaths of the recirculation eductor c116 and/or of the heat recuperator c124 flow to their respective locations along the recirculation pathway c104 or the exhaust gas pathway c120, and are thereby differentiated from a heat-capture pathway c133.

In some embodiments, a heat-capture pathway c133 may utilize a cooling fluid that remains fluidly separate from the primary flowpath c131. For example, a heat-capture pathway c133 may utilize a chiller working fluid (e.g., a refrigerant), such as from a chiller assembly A40, as described herein. Additionally, or in the alternative, a heat-capture pathway c133 may utilize an engine-working fluid, such as from a working-fluid pathway c110, as described herein.

FIGS. 4 and 5 show an exemplary heat-capture pathway c133. As shown, a heat-capture pathway c133 may provide cooling to an interface between a heater body c100 and another portion an engine assembly 900. The heat-capture pathway c133 may provide cooling to a portion of the heater body c100 that includes a working-fluid body c108, a piston body c700, and/or a regenerator body c800. The heat-capture pathway c133 may additionally or alternatively provide cooling to a portion of the heater body c100 that interfaces with a working-fluid body c108, a piston body c700, and/or a regenerator body c800. The heat-capture pathway c133 may also return heat to the heater body c100, such as to an interior heater body-portion c100A of the heater body, such as a combustor body c400. As shown, the heat-capture pathway c133 may provide cooling to an interface between the heater body c100 and an engine body c050. In some embodiments, the heat-capture pathway c133 may provide cooling to a portion of the heater body c100 that interfaces with the engine body c050, such as to a working-fluid body c108, a piston body c700, and/or a regenerator body c800. As shown in FIG. 4, the heat-capture pathway c133 may fluidly communicate with an intake pathway c118, and may utilize intake air from the intake air pathway c118. Additionally, or in the alternative, the heat-capture pathway c133 may fluidly communicate with a cooling jacket c128 and may utilize a fluid such as intake air from the cooling jacket c128.

As shown in FIG. 5, a heat-capture pathway c133 may circumferentially surround at least a portion of a piston chamber c112. A first heat-capture pathway-portion c133A of the heat-capture pathway c133 may flow circumferentially around a first semiannular piston chamber-portion c112A of the piston chamber c112. A second heat-capture pathway-portion c133B may flow circumferentially around a second semiannular piston chamber-portion c112B. The first heat-capture pathway-portion c133A and the second heat-capture pathway-portion c133B may reunite and/or fluidly communicate at an inward perimeter piston chamber-portion c112C of the piston chamber c112. As shown, the first heat-capture pathway-portion c133A and the second heat-capture pathway-portion c133B first heat-capture pathway-portion c133A and the second heat-capture pathway-portion c133B reunite, without fluidly communicating, at the inward perimeter piston chamber-portion c112C. In some embodiments, the heat-capture pathway c133 (e.g., the first heat-capture pathway-portion c133A and/or the second heat-capture pathway-portion c133A) may have a heat transfer relationship with a thermal expansion joint c135. For example, as shown, the heat-capture pathway c133 may include a hairpin c133D that follows a perimeter of the thermal expansion joint c135.

In some embodiments, a fluid flowing through the heat-capture pathway c133 may fluidly communicate with the primary flowpath c121, and fluid flowing through the heat-capture pathway c133 may be discharged from the heat-capture pathway c133 to the primary flowpath c121. As shown, the heat-capture pathway c133 may fluidly communicate with the recirculation pathway c104, such as at the combustion chamber c104. In some embodiments, fluid in the heat-capture pathway c133 may discharge into the combustion chamber c104 through a distal portion of the combustion chamber c102. The distal portion of the combustion chamber c104 may include a plurality of openings providing fluid communication with the heat-capture pathway c133. The plurality of openings may include a plurality of pore-like openings c137A circumferentially surrounding the vortex conditioner c137 and/or disposed about the vortex conditioner c137. The heat-capture pathway c133 may transect at least some of the distal portion of the combustion chamber C102A, thereby providing cooling to the combustion chamber c102. In some embodiments, the heat-capture pathway c133 may include a plurality of spiral-heat-capture pathways c133E disposed about the distal portion of the combustion chamber C102A. In some embodiments, heat-capture fluid in the heat-capture pathway c133 may have a heat transfer relationship with a portion a heater body c100 that would be capable of exceeding a threshold temperature during operations, such as a threshold temperature determined in relation to a melting temperature, whereas the heat-capture fluid operates to maintain such portion of the heater body c100 below such threshold temperature during operations.

Now referring to FIGS. 6A and 6B, and 7A and 7B, exemplary combustor bodies c400 will be described. The presently disclosed combustor bodies c400 may define part of a heater body c100 and/or a closed-cycle engine c002. For example, a combustor body c400 may define at least a portion of a monolithic body or a monolithic body-segment. Such monolithic body or monolithic body-segment may define at least a portion of the heater body c100 and/or the closed-cycle engine c002. Additionally, or in the alternative, the presently disclosed combustor bodies c400 may be provided as a separate component, whether for use in connection with a heater body c100, a closed-cycle engine c002, or any other setting whether related or unrelated to a heater body c100 or a closed-cycle engine c002. At least a portion of the combustor body c400 may define a combustion chamber c102 and/or a conditioning conduit c122. While the heater bodies c100 depicted in the figures may show one combustor body c400 and/or one combustion chamber c102 and/or one conditioning conduit c122, it will be appreciated that a heater body c100 may include a plurality of combustor bodies c400 and/or a plurality of combustion chambers c102 and/or a plurality of conditioning conduits c122. For example, a heater body c100 may include one or more combustor bodies c400, and/or a combustor body c400 may include one or more combustion chambers c102 and/or one or more conditioning conduits c122. Exemplary heater bodies c100 and/or combustor bodies c400 may be configured for single-stage combustion and/or multi-stage combustion. A heater body c100 and/or a combustor body c400 configured for multi-stage combustion may include two, three, four, or more combustion zones.

As shown, an exemplary combustor body c400 may include a combustion chamber c102 and a conditioning conduit c122 circumferentially surrounding at least a portion of the combustion chamber c102. The combustion chamber c102 may be disposed annularly about an axis c204, or the combustion chamber may be off-center from the axis c204. In some embodiments, a plurality of combustion chambers c102 may be circumferentially spaced about the axis c204. The combustion chamber c102 may include an annular combustion chamber wall c406. An inward portion of the annular combustion chamber wall c406 may define at least a portion of the combustion chamber c102. The conditioning conduit c122 may include an outward annular conditioning conduit wall c408 circumferentially surrounding the combustion chamber c122, and an inward annular conditioning conduit wall c410 circumferentially surrounding the outward annular conditioning conduit wall c408. An outward portion of the annular combustion chamber wall c406 may define at least a portion of the inward annular conditioning conduit wall c410. The inward portion of the annular combustion chamber wall c406 and the outward portion of the annular combustion chamber wall c406 may adjoin one another at a distal end c202 of the combustion chamber c102.

The combustion chamber c102 may include a combustion chamber outlet c412 disposed about a proximal portion c202 of the combustion chamber c102. For example, the combustion chamber outlet c412 may be disposed about a proximal portion of an annular combustion chamber wall c406. A combustion chamber c102 may include a single combustion chamber outlet c412 or a plurality of combustion chamber outlets c412, and the combustion chamber outlet or outlets c412 may be oblique to the combustion chamber c102. For example, a plurality of combustion chamber outlets c412 may be circumferentially spaced about a proximal portion c202 of the combustion chamber c102, such as about a proximal portion c202 of the annular combustion chamber wall c406.

The conditioning conduit c122 may fluidly communicate with the combustion chamber c102 at a distal portion of the combustion chamber c102. The conditioning conduit c122 may include a conditioning conduit inlet c414 disposed about a proximal portion c202 of the conditioning conduit c122. For example, the conditioning conduit inlet c414 may be disposed about a proximal portion of the outward annular conditioning conduit wall c408. A conditioning conduit c122 may include a single conditioning conduit inlet c414 or a plurality of conditioning conduit inlets c414, and the conditioning conduit inlet or inlets c414 may be oblique to the conditioning conduit c120. For example, a plurality of conditioning conduit inlets c414 may be circumferentially spaced about a proximal portion c202 of the conditioning conduit c122, such as about a proximal portion c202 of the outward annular conditioning conduit wall c408.

The inward annular conditioning conduit wall c410 may be defined at least in part by the annular combustion chamber wall c406. In some embodiments, a portion of the inward annular conditioning conduit wall c410 may be separated from the annular combustion chamber wall c406, such that the inward annular conditioning conduit wall c410 and the annular combustion chamber wall c406 define an insulating space therebetween (not shown). For example, a medial portion of the inward annular conditioning conduit wall c410 may be separated from the annular combustion chamber wall c406 so as to define such an insulating space.

As shown in FIGS. 6A and 6B, the conditioning conduit c122 may define at least a portion of the recirculation pathway c104. The portion of the recirculation pathway c104 defined by the conditioning conduit c122 may sometimes be referred to as a conditioning conduit pathway c416. The conditioning conduit pathway c416 may be defined at least in part by the inward annular conditioning conduit wall c410 and the outward annular conditioning conduit wall c408.

In exemplary embodiments, the one or more conditioning conduit inlets c414 may be disposed about a proximal portion c200 of the conditioning conduit c122 and oriented oblique to the conditioning conduit c122. For example, the one or more conditioning conduit inlets c414 may be oblique to the outward annular conditioning conduit wall c408 and/or the inward annular conditioning conduit wall c410. The one or more conditioning conduit inlets c414 may respectively include a motive pathway c418 and an eduction pathway c420 fluidly communicating with the conditioning conduit c122. As shown in FIGS. 6A and 6B, a plurality of conditioning conduit inlets c412 may include a plurality of motive pathways c418 and a plurality of eduction pathways c420 circumferentially spaced about the conditioning conduit c122.

The motive pathway c418 (or plurality of motive pathways c418) and the eduction pathway c420 (or plurality of eduction pathway c420) may be defined at least in part by an eductor body c300. The motive pathway c418 or plurality of motive pathways define a portion of an intake air pathway and the eduction pathway or plurality of eduction pathways define a portion of a recirculation pathway. The eduction pathway c420 and the motive pathway c418 may be adjacent to one another, such that intake air flowing through the motive pathway c418 may accelerate and entrain combustion gas from the eduction pathway c420 so as to move circulating combustion gas into the conditioning conduit c122. The motive pathway c418 and the eduction pathway c420 are preferably oriented oblique to the conditioning conduit c122 (e.g., oblique to the outward annular conditioning conduit wall c408 and/or the inward annular conditioning conduit wall c410), such that intake air and combustion gas flowing into the conditioning conduit may readily establish a helical flow pattern through the conditioning conduit c122.

In exemplary embodiments, the one or more combustion chamber outlets c412 may be disposed about a proximal portion c200 of the combustion chamber c102 and oriented oblique to the combustion chamber c102. For example, the one or more combustion chamber outlets c412 may be oblique to the annular combustion chamber wall c406. The one or more combustion chamber outlets c412 may fluidly communicate with a corresponding plurality of combustion-gas pathways c422 circumferentially spaced about the combustion chamber c102. The plurality of combustion-gas pathways c422 may fluidly communicate with a respective portion of the combustion chamber c102. Respective combustion-gas pathways c422 may extend in a radial, circumferential, and/or tangential direction relative to the combustion chamber c102. For example, the respective combustion-gas pathways c422 may concentrically spiral radially or circumferentially outward from the combustion chamber. The respective combustion-gas pathways c422 may extend annularly or semi-annularly along a spiral or spiral arc relative to the combustion chamber and/or the longitudinal axis c204 thereof. As shown in FIGS. 6A and 6B, the plurality of combustion-gas pathways c422 define at least a portion of a hot-side heat exchanger body c600. The oblique orientation of the one or more conditioning conduit inlets c414 and/or of the one or more combustion chamber outlets c412 may cause combustion gas to swirl through the conditioning conduit c122, for example, from a proximal portion of the conditioning conduit c122 to a distal portion of the conditioning conduit c122 and through the combustion chamber c102 from a distal portion of the combustion chamber c102 to a proximal portion of the combustion chamber 102.

The swirling combustion gas may provide a bidirectional coaxial vortex flow field. When the combustor body c400 includes a conditioning conduit c122, the conditioning conduit c122 provides separation between an outward portion of the bidirectional coaxial vortex flow field and an inward portion of the bidirectional coaxial vortex flow field, the conditioning conduit defining a pathway for the outward portion of the bidirectional coaxial vortex flow field and the combustion chamber defining a pathway for the inward portion of the bidirectional coaxial vortex flow field. Such separation of the bidirectional coaxial vortex flow field provided by the conditioning conduit c122 may enhance combustion dynamics, for example, by reducing shear between the outward and inward portions of the bidirectional coaxial vortex flow field.

In some embodiments, the annular combustion chamber wall c406 may have a Coanda surface c424 disposed at a distal end thereof defining a transition between an inner annular portion and an outer annular portion of the annular combustion chamber wall c406. The Coanda surface c424 may be operable at least in part to draw combustion gas from the conditioning conduit c122 into the combustion chamber c102. A “Coanda surface” refers to a curved surface that creates a zone of reduced pressure in the immediate proximity of such curved surface. This pressure drop entrains and accelerates fluid along the contour of the surface, which is sometimes referred to as the “Coanda effect.” The Coanda effect is the phenomena in which a flow attaches itself to a nearby surface and remains attached even though the surface curves away from the initial direction of flow. Characteristic of the Coanda effect, fluid tends to flow over the surface closely, seemingly “clinging to” or “hugging” the surface. As such, the Coanda effect can be used to change the direction of the combustion gas swirling through the conditioning conduit c122 and into the combustion chamber c122. In doing so, a combustion flame c426 may be surrounded by a flow of cooler, uncombusted or partially combusted combustion gas c428, thereby form a boundary layer separating the flame c426 from the annular combustion chamber wall c406.

In some embodiments, the combustor body c400 may include a combustor cap c210 disposed axially adjacent to a distal portion of the conditioning conduit c122. The combustor cap c210 may be operably coupled to the combustor body c400, for example, using bolts (not shown) insertable into bolt holes c430. Alternatively, the combustor cap c210 may define a portion of a monolithic body or a monolithic body-segment that includes at least a portion of the combustor body c400. As yet another alternative, the combustor cap c210 may be integrally formed with at least a portion of the combustor body c400. In an exemplary embodiment, the combustor cap c210 may be operably coupled to the conditioning conduit body c404, or the combustor cap c210 may define a portion of the conditioning conduit body c404 or may be integrally formed with the conditioning conduit body c404.

As shown in FIGS. 6A and 6B, the combustor cap c210 includes an inward combustor cap wall c432 defining a portion of the recirculation pathway c104. The portion of the recirculating pathway c104 including the inward combustor cap wall c432 may provide fluid communication between the conditioning conduit c122 and the combustion chamber c102 at a distal portion of the combustion chamber c102, and the combustor cap c210 may be operable at least in part to direct combustion gas from the conditioning conduit c122 to the combustion chamber c102. The combustor cap c210 may be disposed axially adjacent to a distal portion c202 of the conditioning conduit c122 and/or the combustion chamber c102.

The combustion chamber c102 and the conditioning conduit c122 may have any desired shape. In various embodiments, the combustion chamber c102 may have a shape including a cylinder and/or a frustum, and the conditioning conduit c122 may have a shape including a cylinder and/or a frustum. As shown in FIGS. 6A and 6B, the combustion chamber c102 and the conditioning conduit c122 respectively have a cylindrical shape. In other embodiments, a portion of the combustion chamber c102 having a cylinder shape may be circumferentially surrounded by a portion of the conditioning conduit c122 having a cylinder shape and/or a portion of the conditioning conduit c122 having a frustum shape. Additionally, or in the alternative, a portion of the combustion chamber c102 having a frustum shape may be circumferentially surrounded by a portion of the conditioning conduit c122 having a cylinder shape and/or a portion of the conditioning conduit c122 having a frustum shape. Such a frustum shape of the combustion chamber c102 and/or of the conditioning conduit c122 may converge proximally and/or diverge proximally.

By way of example, a first portion of a combustion chamber c102 may have a first shape that includes a cylinder, and the first portion of the combustion chamber c102 may be circumferentially surrounded by a second portion of the conditioning conduit c122 having a second shape that includes a cylinder and/or a frustum. Additionally, or in the alternative, a third portion of the combustion chamber c102 may have a third shape that includes a cylinder and/or a frustum, and the third portion of the combustion chamber c102 may be circumferentially surrounded by a fourth portion of the conditioning conduit c122 having a fourth shape that includes a cylinder. Further in addition or in the alternative, a fifth portion of the combustion chamber c102 may have a fifth shape that includes a frustum diverging proximally, and the fifth portion of the combustion chamber c102 may be circumferentially surrounded by a sixth portion of the conditioning conduit c122 having a sixth shape that includes a frustum converging proximally and/or a frustum diverging proximally. Still further in addition or in the alternative, a seventh portion of the combustion chamber c102 may have a seventh shape that includes a frustum diverging proximally, and the seventh portion of the combustion chamber c102 may be circumferentially surrounded by an eighth portion of the conditioning conduit having an eighth shape that includes a frustum converging proximally and/or a frustum diverging proximally.

Referring now to FIG. 6B, in some embodiments, a combustor body c400 may include one or more aerodynamic features c434. The one or more aerodynamic features c434 may be disposed about at least a portion of the combustion chamber c102 and/or at least a portion of the conditioning conduit c122, such as the annular combustion chamber wall c406 (e.g. an inward surface and/or an outward surface thereof), the outward annular conditioning conduit wall c408, and/or the inward annular conditioning conduit wall c410. The one or more aerodynamic features c434 may be configured to condition the flow of combustion gas c428 flowing through the conditioning conduit c122, such as by swirling the flow of combustion gas c428. Additionally, or in the alternative, the one or more aerodynamic features c434 may be configured to condition the flow of combustion gas c428 or the flame c426 flowing through the combustion chamber c102, such as by swirling the flow of combustion gas c428 and/or flame c426. For example, the one or more aerodynamic features c434 may include a fin, a ridge, a groove, a contour, and/or the like disposed about the combustion chamber c102 and/or the conditioning conduit c122.

The one or more aerodynamic features c434 may followed a helical orientation along the combustion chamber c102 and/or the conditioning conduit c122. The helical orientation of the one or more aerodynamic features c434 may help condition the flow of combustion gas c428 and/or the flame c426 in a helical path. For example, the combustion gas c428 and/or the flame c426 may follow a helical path that depends at least in part on the slope of the helical orientation of the one or more aerodynamic features c434. Additionally, or in the alternative, such helical path of the combustion gas c428 and/or the flame c426 may depend on the size, number, and/or spacing of the one or more aerodynamic features c434. In an exemplary embodiment, the one or more one or more aerodynamic features c434 may provide a bidirectional coaxial vortex flow field, which may enhance heat transfer of the flame c426 to the hot-side heater body c106 and/or may protect the combustion chamber wall c406 from receiving excessive heat from the flame c426.

As shown in FIG. 6B, the one or more aerodynamic features c434 may include a first helical conditioning ridge c436 be disposed about the annular combustion chamber wall c406 (e.g. an outward surface thereof). Additionally, or in the alternative, the one or more aerodynamic features c434 may include a second helical conditioning ridge c438 disposed about the inward annular conditioning conduit wall c410 and/or a third helical conditioning ridge c440 disposed about the outward annular conditioning conduit wall c408.

Still referring to FIGS. 6A and 6B, the combustor body c400 and/or the combustion chamber c102 may have an axial length selected based at least in part on a desired flame length and/or a corresponding combustion time. In some embodiments, the combustion time may be from 1 to 10 milliseconds, such as from 2 to 4 milliseconds. The combustion time may be at least 1 millisecond, at least 2 milliseconds, or at least 5 milliseconds. The combustion time may be less than 10 milliseconds, less than 7 milliseconds, or less than 3 milliseconds.

The flame c426 may have an axial length extending all or a portion of the combustion chamber c102. In some embodiments, the flame c426 may extend though one or more combustion chamber outlets c412 and into the hot-side heat exchanger c106. The hot-side heat exchanger c106 may include working-fluid pathways c110; however, in some embodiments, the working-fluid pathways c110 may be omitted from a radially or concentrically inward portion of the hot-side heat exchanger c106 so as to facilitate the flame c426 flowing into the hot-side heat exchanger c106. Such a radially-inward portion of the hot-side heat exchanger c106 may define a combustion zone where combustion may occur in the hot-side heat exchanger c106. The combustion that occurs in the hot-side heat exchanger may represent an extension of combustion that occurs in the combustion chamber c102, such as in the case of a flame that extends from the combustion chamber into the hot-side heat exchanger c106. The radially-inward portion of the hot-side heat exchanger c106 may additionally/or alternatively support stable combustion separate and distinct from the combustion that occurs in the combustion chamber c10. For example, a first flame c426 in the combustion chamber may quench upstream from the hot-side heat exchanger c106, and a second flame c426 may be established and stabilize in the radially-inward portion of the hot-side heat exchanger c106.

The radially-inward portion of the hot-side heat exchanger c106 may sometimes be referred to as a second combustion chamber c448, in which case, the combustion chamber c102 may be referred to as a first combustion chamber c102. In some embodiments, the flame c426 may extend into the combustion chamber c448. Additionally, or alternatively, a second flame c426 may exist in the second combustion chamber c448, defining a combustion zone that is separate from a combustion zone in the second combustion chamber c448 may include a plurality of combustion fins c450 circumferentially spaced about the combustion chamber c102. The combustion fins c450 may occupy a region of the hot-side heat exchanger c106 configured for stable combustion to occur. Combustion may occur in the region of the hot-side heat exchanger c106 where the combustion fins c450 are located at least in part by the combustion fins c450 being heated to a sufficiently high temperature during operation to prevent flame quenching and/or promote an extended flame length.

The plurality of combustion fins c450 may spiral concentrically relative to the combustion chamber c102 and/or the longitudinal axis c204 thereof. The plurality of combustion fins c450 may be configured and arranged as spirals or spiral arcs, disposed annularly or semi-annularly, relative to the combustion chamber c102 and/or the longitudinal axis c204 thereof. The combustion fins c450 may be concentrically nested with one another. Concentrically nested combustion fins c450 may be configured as an array of substantially concentric spirals and/or an array of substantially concentric spiral arcs. By way of example, a spiral or spiral arc, such as in an array of substantially concentric spirals or spiral arcs, may correspond to at least a portion of an Archimedean spiral, a Cornu spiral, a Fermat's spiral, a hyperbolic spiral, a logarithmic spiral, a Fibonacchi spiral, an involute, or a squircular spiral, as well as combinations of these.

Upstream portions of the respective combustion-gas pathways c422 may fluidly communicate with the combustion chamber c102 at respective circumferential locations about the perimeter of the combustion chamber c102. Downstream portion of the respective combustion-gas pathways c422 may fluidly communicating with corresponding heating fluid pathways c602 of the hot-side heat exchanger c106 (e.g. FIGS. 29, 30A, and 30B). Such combustion fins c450 may concurrently define at least a portion of the second combustion chamber c448 and at least a portion of the hot-side heat exchanger c106. The combustion fins c450 may become red-hot, encouraging a sustained combustion flame within the second combustion chamber c448. The second combustion chamber c448 may allow combustion to take place at an air-to-fuel ratio closer to the stoichiometric air-to-fuel ratio.

The combustor body c400 may include one or more features of the combustion chamber c102 and/or one or more features of the conditioning conduit c122 configured to burn fuel in a lean combustion environment. For example, the conditioning conduit c122 may include one or more conditioning conduit inlets c414 dimensionally configured to provide sufficient combustion gas flow for a lean combustion environment. Additionally, or in the alternative, the one or more features of the combustion chamber c102 may include one or more combustion chamber outlets dimensionally configured to provide sufficient combustion gas flow for a lean combustion environment. The combustor body c400 may include one or more fuel nozzles, and the one or more fuel nozzles may be configured to provide a fuel flow sufficient for a lean combustion environment.

With respect to the one or more conditioning conduit inlets c414, the lean combustion environment may be provided by one or more motive pathways c418 and/or one or more eduction pathways c420. The one or more motive pathways c418 may be dimensionally configured to supply the conditioning conduit c122 and/or the combustion chamber c102 with sufficient intake air to from the intake air pathway c118 to provide a lean combustion environment. Additionally, or in the alternative, the one or more motive pathways c418 may be dimensionally configured to accelerate and entrain sufficient combustion gas from the recirculation pathway c104 to provide a lean combustion environment. The one or more eduction pathways c420 may be dimensionally configured to recirculate sufficient combustion gas from the recirculation pathway c104 to provide a lean combustion environment.

A lean combustion environment may be characterized by an equivalence ratio, which is the ratio of the actual fuel-to-air ratio to the stoichiometric fuel-to-air ratio. An exemplary lean combustion environment may include an equivalence ratio of 0.6 to 1.0, such as an equivalence ratio of 0.7 to 0.8. The equivalence ratio may be at least 0.6, such as at least 0.8. The equivalence ratio may be less than 1.0, such as less than 0.7. An exemplary lean combustion environment may include an air-to-fuel ratio of from 40:1 to 90:1 by mass, or from 55:1 to 75:1 by mass. The air-to-fuel ratio may be at least 40:1 by mass, such as at least 55:1 by mass. The air-to-fuel ratio may be less than 90:1 by mass, such as less than 75:1 by mass.

The combustor body c400 may include one or more features of the combustion chamber c102 and/or one or more features of the conditioning conduit c122 configured to circulate at least a portion of the combustion gas by volume and to introduce a balance of the combustion gas as intake air. For example, the conditioning conduit c122 may include one or more conditioning conduit inlets c414 dimensionally configured to circulate at least a portion of the combustion gas by volume and to introduce a balance of the combustion gas as intake air. Additionally, or in the alternative, the one or more features of the combustion chamber c102 may include one or more combustion chamber outlets dimensionally configured to circulate from at least a portion the combustion gas by volume and to introduce a balance of the combustion gas as intake air.

The volume of circulating combustion gas may be from about 10% to about 90% of the combustion gas, such as from about 30% to about 70% of the combustion gas, such as from about 40% to about 60% of the combustion, with the balance of the combustion gas as being intake air. The volume of intake air included in the combustion gas may be from about 10% to about 90% of the combustion gas, such as from about 30% to about 70% of the combustion gas, such as from about 40% to about 60% of the combustion, with the balance being circulated combustion gas. However, in some embodiments the combustor body c400 may utilize 100% intake air and/or 100% circulating combustion gas.

In some embodiments, a cooling jacket c442 disposed within the at least a portion of the combustor body c400. The cooling jacket may define a pathway for a cooling fluid to flow within the combustor body c400. The flow of fluid cooling fluid may provide cooling to the combustor body c400. The cooling jacket c442 may fluidly communicate with the intake air pathway c118, the recirculation pathway c104, and/or the working-fluid pathway c110. By way of example, as shown in FIG. 6A, a cooling jacket c442 may be disposed between at least a portion of the inward portion of the annular combustion chamber wall c406 and the outward portion of the annular combustion chamber wall c406, with the cooling jacket c442 fluidly communicating with at least one of the one or more motive pathways c418. Additionally, or in the alternative, the cooling jacket c442 shown in FIG. 6A may fluidly communicate with at least one of the one or more eduction pathways c420. When the cooling fluid for the cooling jacket includes intake air and/or combustion gas, the combustor body c400 may include one or more cooling-jacket outlets c444, allowing the cooling fluid to flow into the conditioning conduct c122 and/or the combustion chamber c102.

Referring again to FIG. 6B, in some embodiments, a combustor body c400 may include a plurality of conditioning pathways c446 traversing the annular combustion chamber wall c406. The conditioning pathways may be disposed about a proximal, medial, and/or axial portion of the combustion chamber c102, for example, traversing a proximal, medial, and/or axial portion of the annular combustion chamber wall c406 and providing fluid communication between the combustion chamber c102 and the conditioning conduit c122.

Now referring to FIGS. 7A and 7B, an exemplary heater body c100 and/or combustor body c400 configured for multi-stage combustion will be described. A combustor body c400 configured for multi-stage combustion may sometimes be referred to as a multi-stage combustor c403. As used herein, the term “multi-stage combustion” refers to a combustion regime that includes at least two combustion zones oriented in serial flow relationship. As used herein, the term “combustion zone” refers to a portion of a combustion gas and/or fuel flowpath configured to support a stable flame c426 under one or more operating conditions. In some embodiments, a combustion zone may include a fuel injection point. For example, a multi-stage combustor may include a plurality of fuel injection points in serial flow relationship that are respectively configured to support a stable flame c426. Additionally, or in the alternative, a multi-stage combustor may include a combustion zone that is configured to support a stable flame c426 by combusting a fuel and/or combustion gas c428 introduced into the flowpath at an upstream combustion zone. For example, a fuel-rich environment may allow for a reburn combustion regime in which fuel injected at a first combustion zone is partially combusted at the first combustion zone and then further combusted at a second combustion zone.

An exemplary multi-stage combustor c403 may include a primary combustion zone and a secondary combustion zone. In some embodiments, a multi-stage combustor may include a tertiary combustion zone. The primary combustion zone may be situated upstream and/or downstream from a secondary combustion zone. A tertiary combustion zone may be located upstream or downstream from a primary combustion zone, and/or upstream or downstream from a secondary combustion zone. As used herein, the term “primary combustion zone” refers to a combustion zone that generates a larger proportion of heat during steady-state operation relative to one or more other combustion zones, such as relative to a secondary combustion zone and/or relative to a secondary and tertiary combustion zone. As used herein, the term “secondary combustion zone” refers to a combustion zone that generates a lesser proportion of heat during steady-state operation relative to another combustion zone, such as relative to a primary combustion zone. The term “tertiary combustion zone” refers to a combustion zone that generates a lesser proportion of heat during steady-state operation relative to a plurality of other combustion zones, such as relative to a primary combustion zone and a secondary combustion zone.

In an exemplary embodiment, a heater body c100 that includes a multi-stage combustor c403 may include a first combustion zone c405 and a second combustion zone c407. The first combustion zone c405 may occupy a distal or medial position relative to the longitudinal axis c204 of the combustion chamber c102. The second combustion zone c407 may occupy a proximal position relative to the longitudinal axis c204 of the combustion chamber c102. The first combustion zone c405 may occupy a radially or concentrically inward position relative to the longitudinal axis c204 of the combustion chamber c102. The second combustion zone c407 may occupy a radially or concentrically outward position relative to the longitudinal axis c204 of the combustion chamber c102 and/or relative to the radially or concentrically inward position of the first combustion zone c405. In some embodiments, the first combustion zone c405 may occupy at least a portion of a vortex flow field, such as a bidirectional vortex flow field. For example, the first combustion zone c405 may occupy at least part of an inward portion of a bidirectional coaxial vortex flow field. The second combustion zone c407 may occupy at least part of a proximal region of the combustion chamber c102. Additionally, or in the alternative, the second combustion zone c407 may occupy at least part of a radially-inward portion of the hot-side heat exchanger c106. For example, the hot-side heat exchanger c106 may define a second combustion chamber c448, and the second combustion zone c407 may occupy at least a portion of the second combustion chamber c448.

The first combustion zone c405 may be located upstream from a heat sink c409 a sufficient distance to allow combustion in the first combustion zone c405 to start, warm up, and stabilize. For example, the heat sink c409 may include at least a portion of the working-fluid bodies c108 and/or at least a portion of the hot-side heat exchanger c106. The working-fluid bodies c108 may have a heat transfer relationship with the hot-side heat exchanger c106. The heat sink c409 may include a plurality of working-fluid pathways c110 that have a heat transfer relationship with the hot-side heat exchanger c108 and/or the plurality of combustion-gas pathways c422. The plurality of heating walls c616 may define at least a portion of the hot-side heat exchanger c106. The hot-side heat exchanger c106 may include a plurality of working-fluid pathways monolithically formed within the plurality of heating walls c616.

Combustion in the second combustion zone c407 may be initiated concurrently with and/or subsequently to initiation of combustion the first combustion zone c405. In some embodiments, combustion in the second combustion zone c407 may be initiated after combustion in the first combustion zone c405 has started, and/or after combustion in the first combustion zone c405 at least partially heated at least a portion of the combustor body c400 proximate to the second combustion zone c407. Additionally, or in the alternative, combustion in the second combustion zone c407 may be initiated after combustion in the first combustion zone c405 has stabilized.

Combustion in the first combustion zone c405 may be operated or sustained as a primary combustion zone. Additionally, or in the alternative, combustion in the first combustion zone c405 may be operated or sustained as a secondary combustion zone, or even as a tertiary combustion zone. In some embodiments, combustion in the first combustion zone c405 may be initially operated or sustained as a primary combustion zone, such as during a warm-up period. After an initial operating period, such as the warm-up period, combustion in the first combustion zone may transition to operation as a secondary combustion zone or a tertiary combustion zone. Combustion in the second combustion zone c407 may be operated or sustained as a primary combustion zone and/or a secondary combustion zone. For example, combustion in the second combustion zone c407 may be operated or sustained as a primary combustion zone after combustion in the first combustion zone c405 has sufficiently heated at least a portion of the combustor body c400 proximate to the second combustion zone c407. As combustion in the first combustion zone c405 transitions to operation as a secondary combustion zone, combustion in the second combustion zone c407 may transition to operation as a primary combustion zone. In some embodiments, combustion in the first combustion zone may be throttled back to a nominal proportion of combustion. For example, combustion in the first combustion zone c405 may operate at a nominal level sufficient to sustain steady combustion at the secondary combustion zone c407.

During operation, such as during steady state operation, combustion in the first combustion zone c405 may support combustion in the second combustion zone c407 by maintaining a supply of heat sufficient to sustain at least a portion of the combustor body c400 proximate to the second combustion zone c407 at a temperature that exceeds a threshold suitable for good combustion and flame characteristics at the second combustion zone c407. Such support from the first combustion zone c405 may advantageously allow the second combustion zone c407 to operate as a primary combustion zone, thereby introducing heat closer to a heat sink such as a working-fluid body c108 and/or a hot-side heat exchanger c106. In some embodiments, a hot-side heat exchanger c106 and/or a working-fluid body c108 may provide an improve heating efficiency with the second combustion zone c407 operating as the primary combustion zone.

As mentioned, in some embodiments, a combustor body c400 may include a plurality of combustion fins c450 circumferentially spaced about the perimeter of the combustion chamber c102 and/or the longitudinal axis c204. The plurality of combustion fins c450 may define a radially or concentrically inward portion of the plurality of combustion-gas pathways c422. The term “combustion-gas pathway” may refer to the portion of a heating fluid pathway c 602 defined by the combustion fins c450. The combustion-gas pathways c422 may be configured and arranged as spirals or spiral arcs, and may be oriented concentrically about the combustion chamber c102 and/or the longitudinal axis c204. The combustion-gas pathways c422 may fluidly communicating with a corresponding plurality of spiral pathways of the hot-side heat exchanger c106. The plurality of combustion fins c450 may respectively define a portion of a corresponding plurality of heating walls c616. Such combustion fins c450 may concurrently define at least a portion of the second combustion chamber c448 and at least a portion of the hot-side heat exchanger c106. The second combustion zone c407 may occupy at least part of the radially or concentrically inward portion of the plurality of combustion-gas pathways c422 defined by the plurality of combustion fins c450.

Regardless of whether the secondary combustion zone c407 includes combustion fins c450, at least a portion of the combustor body c400 proximate to the secondary combustion zone c407 may become red-hot, encouraging a sustained combustion flame within the secondary combustion zone c407. Combustion in the secondary combustion zone c407 may take place at an air-to-fuel ratio closer to the stoichiometric air-to-fuel ratio, with or without secondary combustion support from the first combustion zone c405.

A heater body c100 that includes a multi-stage combustor c403 may include a cool-zone fuel injector c411 and a hot-zone fuel injector c413. However, in some embodiments, a multi-stage combustor c403 may be configured to sustain combustion in a plurality of combustion zones with only a single fuel injector, such as a cool-zone fuel injector c411 or a hot-zone fuel injector c413. The cool-zone fuel injector c411 may occupy a distal position relative to the longitudinal axis c204 of the combustion chamber c102. The cool-zone fuel injector c411 may occupy a radially or concentrically inward position relative to the longitudinal axis c204 of the combustion chamber c102. In some embodiments, a hot-zone fuel injector c413 may occupy a proximal position relative to the longitudinal axis c204 of the combustion chamber c102. The hot-zone fuel injector c413 may occupy a radially or concentrically outward position relative to the longitudinal axis c204 of the combustion chamber c102 and/or relative to the radially or concentrically inward position of the cool-zone fuel injector c411. The cool-zone fuel injector c411 may coincide with the first combustion zone c405. Additionally, or in the alternative, the first fuel injector may be located upstream from the first combustion zone c405. For example, the cool-zone fuel injector c411 may be operably coupled to a combustor cap c210, such as at a nozzle port c212. The hot-zone fuel injector c413 may coincide with the second combustion zone c407. Additionally, or in the alternative, the hot-zone fuel injector c413 may be located upstream from the second combustion zone c407.

In some embodiments, a heater body c100 and/or a combustor body c400 may include one or more fuel injectors monolithically integrated with a distal portion of the combustor body c400 and/or a radially or concentrically inward portion of the combustor body c400. The one or more fuel injectors may be monolithically integrated with a radially or concentrically inward portion of the hot-side heat exchanger c106. For example, a plurality of a hot-zone fuel injectors c413 may be monolithically integrated with a distal portion of the combustor body c400 and/or a radially or concentrically inward portion of the plurality of combustion-gas pathways c616 of the hot-side heat exchanger c106. The one or more fuel injectors may be monolithically integrated with the plurality of heating walls c616 and/or the plurality of combustion fins c450. Such plurality of hot-zone fuel injectors c413 may operate as a collective unit and may be referred to collectively as a hot-zone fuel injector c413. Additionally, or in the alternative, such plurality of hot-zone fuel injectors c413 may operate independently from one another and may be referred to individually as a hot-zone fuel injector c413.

One or more hot-zone fuel pathways c415 may be monolithically integrated with at least part of a distal portion of the combustor body c400 and/or a radially or concentrically inward portion of the hot-side heat exchanger c106. The one or more hot-zone fuel pathways c415 may be configured to supply fuel for combustion at the second combustion zone c407. For example, as shown in FIGS. 7A and 7B, a plurality of hot-zone fuel pathways c415 may be defined within respective ones of a plurality of heating walls c616 of a hot-side heat exchanger c106. Additionally, or in the alternative, one or more hot-zone fuel pathways c415 may be defined within a distal portion of the combustor body c400.

As shown, a plurality of heating walls c616 may include a heat sink c409, such as a hot-side heat exchanger c106 and/or a working-fluid body c108. The plurality of heating walls c616 may occupy a radially concentrically outward position relative to the combustion chamber c102. The plurality of heating walls c616 may define a corresponding plurality of combustion-gas pathways c422, such as spiral pathway or a spiral arc pathway, fluidly communicating with the combustion chamber c402 at circumferentially spaced locations about the combustion chamber c402. The combustion-gas pathways c422 may fluidly communicate with a proximal portion c200 of the combustion chamber c102. The plurality of combustion-gas pathways c422 may follow an annular or semiannular spiral trajectory relative to the combustion chamber c102 and/or the longitudinal axis c204 thereof.

The hot-zone fuel pathways c415 may fluidly communicate with respective ones of a plurality of combustion-gas pathways c422 of the hot-side heat exchanger c106, such as at respective ones of a plurality of heating walls c616 and/or combustion fins c450. The plurality of heating walls c616 and/or combustion fins c450 may have a plurality of openings c451 (e.g., pore-like openings) that fluidly communicate with the plurality of combustion-gas pathways c422 of the hot-side heat exchanger c106 and define the hot-zone fuel injectors c413.

In some embodiments, at least a portion of the hot-zone fuel pathways c415 may define a vaporization heat exchanger c417 that provides a heat transfer relationship between a combustion flame c426 and fuel within the hot-zone fuel pathways c415, and or between hot combustion gas c426 fuel within the hot-zone fuel pathways c415. The vaporization heat exchanger c417 may be effective to vaporize fuel (e.g., liquid fuel), such as when the fuel is within the hot-zone fuel pathways c415 and/or the hot-zone fuel injectors c413, or as the fuel is discharged from the openings (e.g., the pore-like openings) of the hot-zone fuel injectors c413.

During operation, heat from the first combustion zone c405 may heat the hot-zone fuel injectors c413 and/or at least a portion of the second combustion zone c407 to a sufficiently high temperature to allow fuel flowing out of the hot-zone fuel injectors c413 to auto-ignite. For example, a distal portion of the combustion chamber c102, and/or a radially or concentrically inward portion of the hot-side heat exchanger c106 (e.g., the combustion fins c450 and/or a radially or concentrically inward portion of the heating walls c616) may operate at a sufficiently high temperature to allow fuel flowing out of the hot-zone fuel injectors c413 to auto-ignite. The flame c426 and/or hot combustion gas c428 may have a temperature of from about 300 C to about 900 C, such as from about 350 C to about 800 C, such as from about 425 C to about 750 C, such as from about 500 C to 600 C. Once the fuel flowing out of the hot-zone fuel injectors c413 auto-ignites, the flame provided by cool-zone fuel injector c411 may be reduced to a minimal length sufficient to support combustion at the second combustion zone c407. In this way, the flame from the cool-zone fuel injector c411 may operate as a pilot burner configured to provide a pilot flame, or ignition source, for combustion in the second combustion zone c407. The pilot flame, or ignition source, provided by the cool-zone fuel injector c411 may support auto-ignition and good combustion of combustion gas c428 and/or fuel c426 flowing from the first combustion zone c405 to the second combustion zone c407, for example, providing a reburn combustion regime. Additionally, or in the alternative, such pilot flame, or ignition source may support auto-ignition and good combustion of fuel supplied by the hot-zone fuel injectors c413.

In some embodiments, the first combustion zone c405 may exhibit a rich combustion environment attributable at least in part to the fuel-to-air ratio resulting from fuel from the cool-zone fuel injector c411. The second combustion zone c407 may exhibit a lean combustion environment attributable at least in part to the fuel-to-air ratio resulting from the rich combustion environment of the first combustion zone c405 and/or fuel from the hot-zone fuel injectors c413. In some embodiments, the first combustion zone c405 may exhibit a lean combustion environment prior to auto-ignition at the second combustion zone c407. Upon auto-ignition at the second combustion zone c407, the first combustion zone c405 may transition to a rich combustion environment. The second combustion zone c407 may thereafter exhibit a lean combustion environment while the first combustion zone c405 may exhibit a rich combustion environment.

As mentioned, a lean combustion environment may be characterized by an equivalence ratio, which is the ratio of the actual fuel-to-air ratio to the stoichiometric fuel-to-air ratio. A rich combustion environment may similarly be characterized by an equivalence ratio. An exemplary lean combustion environment may include an equivalence ratio of from about 0.5 to about 1.0, such as from about 0.6 to about 0.9, or from about 0.7 to about 0.8 An exemplary rich combustion environment may include an equivalence ratio of from less than about 0.1 to about 0.5, such as from less than about 0.1 to about 0.2. By way of example, the first combustion zone c405 may exhibit an aforementioned “lean” equivalence ratio prior to auto-ignition at the second combustion zone c407, such as from about 0.5 to about 1.0, or any other suitable lean equivalence ratio. Upon auto-ignition at the second combustion zone c407, the first combustion zone c405 may transition to a “rich” equivalence ratio, such as from less than about 0.1 to about 0.5, or any other suitable rich equivalence ratio. The second combustion zone, meanwhile, may exhibit a “lean” equivalence ratio, such as from about 0.5 to 1.0, or any other suitable lean equivalence ratio. In exemplary embodiments, fuel may be supplied to the cool-zone fuel injector without pre-mix air, for example, to provide a rich combustion environment.

As shown in FIG. 7B, in some embodiments, the second combustion zone c407 may occupy one or more regions of the plurality of combustion-gas pathways c422 of the hot-side heat exchanger c106. For example, respective combustion-gas pathways c422 may include a respective second combustion zone-segment c407A.

In some embodiments, the combustion-gas pathways c422 may include a burner zone c419 configured to support combustion and/or flame stabilization within the second combustion zone c407 and/or within the respective combustion zone-segments c407A. The burner zone c419 may be defined by a plurality of burner gap, GB, c421 defined in the respective heating walls c616 and oriented along the flowpath of the respective combustion-gas pathways c422. The burner gaps c421 may be located downstream from the hot-zone fuel injectors c413, such as between respective combustion fins c450 and corresponding downstream portions of the heating walls c616. A burner gap c421 may define a gap between a combustion fin c450 and a corresponding heating wall c616. The burner gaps c421 may include an open space, a mesh, a three-dimensional lattice, a porous medium, or the like. The burner zone c419 may coincide with at least a portion of the second combustion zone c407. Additionally, or in the alternative, the second combustion zone c407 may at least partially coincide with the plurality of burner gaps c421.

In some embodiments, a combustion chamber c104 may include a vortex conditioner c137, as shown, for example, in FIGS. 4 and 7A. The vortex conditioner c137 may be monolithically integrated with a proximal portion of the combustion chamber c102. The vortex conditioner c137 may be configured at least in part to establish and/or sustain a vortex flow field that includes the combustion gas c428 and/or the flame c426. For example, the vortex conditioner c137 may be configured at least in part to establish and/or sustain a bidirectional coaxial vortex flow field, which may enhance heat transfer of the flame c426 to the hot-side heater body c106 and/or may protect the combustion chamber wall c406 from receiving excessive heat from the flame c426. The second combustion zone c407 may occupy a radially or concentrically outward position relative to the vortex conditioner c137. As shown, the vortex conditioner c137 may have a conical or frustoconical shape projecting into the combustion chamber c102, such as along the longitudinal axis c204; however, other shapes are also envisioned. In some embodiments, a conical or frustoconical shape of the vortex conditioner c137, and/or the location and/or dimensions thereof, may at least partially contribute to the vortex flow field (e.g., the bidirectional coaxial vortex flow field) of the combustion gas c428 and/or the flame c426. A vortex conditioner c137 may be included with a heater body c100 and/or a combustor body c400 configured for single-stage and/or multi-stage combustion.

Now referring to FIGS. 8A-8C, further exemplary combustor bodies c400 will be described. As shown in FIG. 8A, an exemplary combustor body c400 may include a venturi c423 in the conditioning conduit pathway c416, such as at a distal portion c202 of the conditioning conduit c122. The combustor body c400 may have a frustoconical configuration. For example, the conditioning conduit c122 may have a frustoconical configuration. Additionally, or in the alternative, the combustion chamber c102 may have a frustoconical configuration. The venturi c423 may be effective to improve mixing and/or reduce pressure drop in fluid flow through the conditioning conduit pathway c416 as the flow transitions form the conditioning conduit pathway c416 to the combustion chamber c102. The venturi c423 may additionally or alternatively induce turbulence, providing a mixing zone for fuel entering the combustion chamber c102 from a fuel nozzle c126, such as a cool-zone fuel injector c111. The venturi c423 may additionally or alternatively accelerate flow into the combustion chamber, such as into the first combustion zone c405. Such improved mixing, reduced pressure drop, and/or flow acceleration may increase combustion efficiency and/or heating efficiency of the heater body c100.

As shown in FIG. 8B, the venturi provides an increase in velocity as the flow of combustion gas and/or intake air along the conditioning conduit pathway c416 transitions form zone “A” to zone “B” at the transition from the conditioning conduit c122 to the combustion chamber c102. The velocity of the flow decreases as the flow advances towards zone “C” within the combustion chamber c102. The venturi c423 may work in cooperation with a Coanda surface c424 to condition flow into the combustion chamber c102. A smoothly converging and diverging flowpath may be effective to reduce pressure drop across the venturi c423.

As shown in FIG. 8C, in some embodiments, the flow of combustion gas and/or intake air in the conditioning conduit pathway c416 may exhibit a tangential velocity gradient that increases from a radially or concentrically inward portion to a radially or concentrically outward portion of the conditioning conduit pathway c416. The tangential velocity gradient may increase as the radius of the conditioning conduit pathway c416 decreases, for example, as the conditioning conduit pathway c416 approaches the venturi c423. Such increase in velocity attributable to the tangential velocity gradient may further enhance mixing at zone “B,” shown in FIGS. 8A and 8B, such as at the venturi c423.

The frustoconical configuration and arrangement of the combustor body c400, including the configuration and arrangement of the conditioning conduit c122 and/or the combustion chamber c102, may be selected at least in part to provide a desired reduction in pressure drop, fluid flow rate, and/or size of the combustor body. For example, pressure drop may be reduced by providing a small convergence angle, θ c425. By contrast, a small convergence angle may correspond to a taller combustor body c400, increasing material cost. Conversely, a large convergence angle, θ c425 may allow for a shorter combustor body c400 but increased pressure drop. These factors may be balanced to determine a suitable frustoconical configuration and arrangement for the combustor body c400.

Now turning to FIGS. 9A-9E, in some embodiments, a combustor body c400 may include one or more combustor vanes c427. The combustor vanes c427 may be configured to condition a flow of combustion gas and/or intake air into the combustion chamber. In some embodiments, the combustor vanes c427 may be configured to induce a vortex or turbulent flow in combustion gas and/or intake air entering the combustion chamber. Such vortex or turbulent flow may improve mixing, for example, providing a mixing zone for fuel entering the combustion chamber 102 from a fuel nozzle c126, such as a cool-zone fuel injector c111. The combustor vanes c427 may be fixed to the combustor cap c210. For example, the combustor vanes c427 may define a monolithic portion of the combustor cap c210. Additionally, or in the alternative, a combustion chamber c102 may include one or more combustor vanes c427, for example, defining a monolithic portion of the combustion chamber c102.

In some embodiments, a plurality of vane rows may be provided. For example, as shown, a combustor body c400 and/or a combustor cap c210 may include three vane rows. As shown in FIG. 9A, a combustor cap c210 may include a first vane row c429A, a second vane row c429B, and/or a third vane row c429C. The respective vane rows may include one or more vanes. The vane rows may be oriented coannularly relative to a longitudinal axis of the combustor body c204.

The first vane row c429A may define a shield flowpath along the wall of the combustion chamber c102. The shield flowpath may provide cooling to the combustion chamber wall. The second vane row c429B may provide a main flowpath. The main flowpath may provide the bulk flow for combustion. The third vane row c429C may provide a premixing flowpath. The premixing flowpath may provide oxygen to mix with fuel prior to combustion.

The respective combustor vanes c427 may have any desired configuration. A combustor vane c427 may have any desired height extending from an inward combustor cap-surface c431. A combustor vane c427 may have a height that runs parallel to the inward combustor cap-surface c431. Additionally, or in the alternative, a combustor vane c427 may have a height that is sloped relative to the inward combustor cap-surface 431. By way of example, FIG. 9B shows an individual combustor vane c427 that has a sloped height relative to the inward combustor cap surface c431.

By way of example, FIGS. 9C-9E show exemplary configurations of combustor vanes c427. The configurations shown are provided by way of example and not to be limiting. As shown in FIG. 9C, a plurality of combustor vanes c427 may have an airfoil-type configuration. Additionally, or in the alternative, a plurality of combustor vanes c427 may have a baffle-type configuration. A plurality of rows of airfoil-type combustor vanes c427 and/or baffle-type combustor vanes c427 may be provided, such as three rows, as shown. A plurality of combustor vanes c427 may additionally or alternatively have a spiral configuration, as shown, for example, in FIG. 9E.

Now turning to FIGS. 10A and 10B, exemplary methods of combusting a fuel will be described. Exemplary methods may be performed in connection with operation of a combustor body c400, a heater body c100, and/or a closed-cycle engine c002 as described herein. As shown in FIG. 10A, an exemplary method c470 may include, at block c472, swirling combustion gas through a conditioning conduit c122, with the combustion gas flowing from a proximal portion of the conditioning conduit c122 to a distal portion of the conditioning conduit c122 while swirling. At block c474, the exemplary method c470 may include swirling the combustion gas through a combustion chamber c102. In the exemplary method c470, the conditioning conduit c122 may circumferentially surround the combustion chamber c102 with the conditioning conduit c122 providing fluid communication with the combustion chamber c102 at a distal portion of the combustion chamber c102. The combustion gas may flow from the distal portion of the conditioning conduit c122 to the distal portion of the combustion chamber c102 and from the distal portion of the combustion chamber c102 to a proximal portion of the combustion chamber c102. At block c476, the exemplary method c470 may include combusting a fuel c426 in the combustion chamber c102. The fuel may be supplied at least in part from the combustion gas flowing from the conditioning conduit c122 to the combustion chamber c102.

The exemplary method c470 may additionally or alternatively include, at block 478, supplying at least a portion of the fuel to the combustion chamber c102 through a fuel nozzle c214 fluidly communicating with a distal portion of the combustion chamber c102. Additionally, or in the alternative, the exemplary method c470 may include supplying at least a portion of the fuel to the combustion chamber through the conditioning conduit. For example, the exemplary method c470 may include, circulating at least a portion of the combustion gas through one or more conditioning conduit inlets c414 disposed about a proximal portion of the conditioning conduit.

At block c480, the exemplary method c470 may include circulating at least a portion of the combustion gas through a recirculation pathway c104, with the recirculation pathway c104 providing fluid communication from a proximal portion of the combustion chamber c102 to a proximal portion of the conditioning conduit c122. The recirculation pathway c104 may include a hot-side heat exchanger c106 and a recirculation eductor c116. The hot-side heat exchanger c106 may fluidly communicate with a proximal portion of the combustion chamber c102 and the recirculation eductor c116 may fluidly communicate with a downstream portion of the hot-side heat exchanger c106 and a proximal portion of the conditioning conduit c122 and/or and a distal portion of the combustion chamber c102. The exemplary method may include combusting at least a portion of the combustion gas circulating through the recirculation pathway c104.

At least a portion of the fuel may be supplied to the combustion chamber c102 through one or more conditioning conduit inlets c414 disposed about a proximal portion of the conditioning conduit c122. Supplying fuel through the one or more conditioning conduit inlets c414 may include supplying fuel through one or more motive pathways c418 and/or one or more eduction pathways c420. The one or more conditioning conduit inlets c414 may be oblique to the conditioning conduit c122, for example, to facilitate swirling of the combustion gas and/or fuel.

Now referring to FIG. 10B, another exemplary method c471 of combusting a fuel will be described. As shown, an exemplary method c471 may include, at block c473, combusting a fuel at a first combustion zone c405; at a block c475, heating a second combustion zone c407; and, at block c477, combusting a fuel at the second combustion zone c407. In some embodiments, an exemplary method c471 may include, at block c479, auto-igniting fuel at the second combustion zone c407. Combusting the fuel at a first combustion zone c405 may include, at block c481, combusting fuel from a cool-zone fuel injector c411 at the first combustion zone c405. Auto-igniting fuel at the second combustion zone c407 may include, at block c483, auto-igniting fuel from the cool-zone fuel injector c411 from a hot-zone fuel injector c413 at the second combustion zone c407. Combusting the fuel at the second combustion zone c407 may include, at block c485, combusting fuel from the cool-zone fuel injector c411 and/or from the hot-zone fuel injector c413 at the second combustion zone c407. Heating the second combustion zone c407 may include, at block c487 vaporizing fuel in a vaporization heat exchanger c417.

In some embodiments, combusting fuel at the first combustion zone c405 may include, at block c489, combusting fuel at the first combustion zone c405 in a lean combustion environment and/or a rich combustion environment. At block c491, combusting fuel at the second combustion zone c407 may include combusting fuel at the second combustion zone c407 in a rich combustion environment. In some embodiments, an exemplary method c471 may include, at bock c493A, combusting fuel at the first combustion zone in a lean combustion environment, and, at block c493B, combusting fuel at the first combustion zone in a rich combustion environment upon having auto-ignited fuel at the second combustion zone. At block c491C, an exemplary method c471 may include combusting fuel at the second combustion zone in a lean combustion environment while combusting fuel at the first combustion zone in a rich combustion environment.

Any one or more parameters may be utilized to control one or more operations of a combustor body c400, a heater body c100, and/or a closed-cycle engine c002 as described herein, including one or more operations in connection with methods of combustion a fuel such as the exemplary methods described herein with reference to FIGS. 10A and 10B. By way of example, an exemplary method of combustion a fuel c470, c471 may include controlling one or more of: a fuel flow (e.g., a fuel flow to a cool-zone fuel injector c411 and/or a hot-zone fuel injector c413), an air flow (e.g., an intake airflow, an exhaust flow, and/or a combustion gas flow).

Now turning to FIG. 11 through FIG. 28, fuel injectors for relatively small or compact apparatuses such as external or internal combustion engines for automotive vehicles, watercraft, or light aircraft, or power units, are limited in spaced such as to inhibit provision of dual-fuel systems. As such, there is a need for fuel injector assemblies that provide dual-fuel systems for relatively small or compact apparatuses.

Embodiments of a fuel injector assembly are provided that may improve atomization and ignition of two or more fuels flowed from the fuel injector assembly. The embodiments shown and described provide a second fuel circuit, through which a liquid or gaseous fuel flows, surrounded at a downstream end by one or more gaseous fluid circuits, such as to provide cooling at the second fuel circuit to mitigate coking and fuel injector deterioration. The fuel injector assembly provided herein provides a compact assembly that may provide dual-fuel combustion for automotive, marine, auxiliary power unit, rotary or fixed wing aircraft, or other vehicles necessitating smaller combustion assemblies.

Referring now to FIG. 11, a cross sectional view of an exemplary embodiment of a fuel injector assembly d100 (“fuel injector d100”) is generally provided. The body d110 of the fuel injector d110 is extended along a lateral direction L between an upstream end d99 and a downstream end d98. A reference fuel injector centerline axis d13 is defined through a cylindrical portion d116 of the body d110. The cylindrical portion d116 of the body d110 is defined circumferentially relative to the reference centerline axis d13 and extended along the lateral direction L. The body d110 further includes a frustoconical portion d117 at the downstream end d98.

The fuel injector d100 includes a first fuel circuit d111 and a second fuel circuit d112 each defined within the body d110. The first fuel circuit d111 and the second fuel circuit d112 are each extended along the lateral direction L from the upstream end d99 to the downstream end d98. The first fuel circuit d111 and the second fuel circuit d112 are each separated circumferentially from one another, such as further depicted in regard to FIGS. 12 through 15.

Referring still to FIG. 11, in various embodiments, the first fuel circuit d111 and the second fuel circuit d112 each extend along a lateral distance d120 of the body d110. The lateral distance d120 of the body d110 is extended from the downstream end d98 (i.e., at a tip corresponding to an output port d105) to the upstream end d99 (i.e., corresponding to an inlet port d108). For a portion of the lateral distance d120, such as depicted at reference dimension d121 extended from the downstream end d98, the first fuel circuit d111 is extended annularly within the body d110. For another portion of the lateral distance d120, such as depicted at reference dimension d122 extended from the downstream end d98, the second fuel circuit d112 is extended annularly within the body d110. In various embodiments, the portion d121 of the lateral distance d120 for which the first fuel circuit d111 is extended circumferentially through the body d110 is greater than the portion d122 of the lateral distance d120 for which the second fuel circuit d112 is extended circumferentially through the body d110. In one embodiment, the portion d122 is 90% or less of the portion d121. In another embodiment, the portion d122 is 75% or less of the portion d121. In still another embodiment, the portion d122 is 50% or less of the portion d121. In various embodiments, the portion d122 is 33% or greater of the portion d121.

Referring now to FIGS. 12 through 15, exemplary embodiments of portions of the fuel injector d100 depicting fuel flows therethrough are provided. During operation of the fuel injector d100, a first flow of fuel d101 and a second flow of fuel d102 are each provided through the body d110 of the fuel injector d100. The first flow of fuel d101 is provided to the first fuel circuit d111 fluidly segregated from the second flow of fuel d102 provided to the second fuel circuit d112. For clarity, FIG. 12 shows only the first flow of fuel d101 through the first fuel circuit d111. Furthermore, for clarity, FIG. 13 shows only the second flow of fuel d102 through the second fuel circuit d112. FIGS. 14 and 15 each depict portions of the fuel injector d100 providing the first flow of fuel d101 and the second flow of fuel d102 each through the fuel injector d100. Referring to FIGS. 11 through 15, the first fuel circuit d111 and the second fuel circuit d112 are each spaced apart from one another along a radial direction R relative to the centerline axis d13. Additionally, the first fuel circuit d111 is extended partly annularly through the body d110 for the non-annular portion (i.e., the difference between portion d121 and the lateral distance d120) of the first fuel circuit d111. Furthermore, the second fuel circuit d112 is extended partly annularly through the body d110 for the non-annular portion (i.e., the difference between portion d122 and the lateral distance d120) of the second fuel circuit d112.

In various embodiments, the first fuel circuit d111 defines a single passage through the body d110 of the fuel injector d100 in which the passage is partly annular from the upstream end d99 (i.e., less than fully annular or otherwise not entirely circumferentially extended) until transitioning (at portion d126) to a full annular passage (at portion d121) at the downstream end d98 of the fuel injector d100. In still various embodiments, the second fuel circuit d112 defines a single passage through the body d110 of the fuel injector d100 in which the passage is partly annular until transitioning (at portion d127) to a full annular passage (at portion d122) at the downstream end d98 of the fuel injector d100, and downstream of where the first fuel circuit d111 transitions to the full annular passage (at portion d121). In one embodiment, the first flow of fuel d101 is particularly a gaseous fuel and the second flow of fuel d102 is a liquid or gaseous fuel. The gaseous first flow of fuel d101 extends circumferentially within portion d121 through the first fuel circuit d111 around the liquid (or gaseous) second flow of fuel d102 extended circumferentially within portion d122 through the second fuel circuit d112. The gaseous first flow of fuel d101 surrounding the liquid second flow of fuel d102 at the second fuel circuit d112 may provide thermal attenuation at the second fuel circuit d112 such as to prevent coking of the liquid second flow of fuel d102 at the relatively hotter downstream end d98 of the fuel injector d100.

Referring now to FIGS. 16 and 17, perspective views of exemplary embodiments of the fuel injector d100 are provided. FIG. 16 provides a view from the downstream end d98 of the fuel injector d100 looking upstream. FIG. 17 provides a view from the upstream end d99 of the fuel injector d100 looking downstream. Referring to FIG. 16, in conjunction with FIGS. 11 through 15, the fuel injector d100 defines a plurality of first fuel injection apertures d115 through the body d110. The plurality of first fuel injection apertures d115 are defined circumferential arrangement through the body d110 relative to the reference centerline axis d13. The plurality of first fuel injection apertures d115 provides a plurality of individual orifices through which the individual streams of the first flow of fuel d101 egress the body d110. In various embodiments, the plurality of first fuel injection apertures d115 defines a jet-in-crossflow (JICF) arrangement through the frusto-conical portion d117 of the body d110.

Referring still to FIG. 16, in conjunction with FIGS. 11 through 15, the fuel injector d100 further defines an annular second fuel injection opening d125 through the body d110. The second fuel injection opening d125 is defined at the downstream end d98 of the fuel injector d100. In various embodiments, the second fuel injection opening d125 is a full annular or completely circumferential opening from which the second flow of fuel d102 egresses the second fuel circuit d112 at least partially as a conical flow of fuel to a combustion chamber.

Referring back to FIG. 13, in various embodiments the body d110 defines a converging-diverging flowpath at the downstream end d98 of the second fuel circuit d112. In one embodiment, the second fuel circuit d112 defines within the full annular portion d122 a converging portion d128 in which a wall converges toward the reference centerline axis d13. The second fuel circuit d112 further defines within the full annular portion d122 a diverging portion d129 in which a wall diverges away from the reference centerline axis d13. In one embodiment, the diverging portion d129 is defined downstream of the converging portion d128. The diverging portion d129 may provide the at least partially conical geometry of the second flow of fuel d102 egressing the second fuel injection opening d125. In various embodiments, the converging portion d128 may be defined at or otherwise corresponding to the frusto-conical portion d117 of the body d110, such as depicted in regard to FIGS. 11 and 15.

Referring still to FIG. 13, the body d110 may further define a vane structure d130 at the second fuel circuit d112. In one embodiment, the vane structure d130 is particularly defined at the downstream end d98 of the fuel injector d100 at the full annular portion d122 of the second fuel circuit d112. The vane structure d130 is configured to impart a circumferential velocity or swirl to the second flow of fuel d102 through the full annular portion d122 of the second fuel circuit d112. In another embodiment, the vane structure d130 may be defined upstream of the full annular portion d122. In a particular embodiment, the vane structure d130 may be defined at the transition portion d127 of the second fuel circuit d112 such as to impart a swirl to the second flow of fuel d102 entering the full annular portion d122 of the second fuel circuit d112 and egresses the second fuel injection opening d125. The vane structure d130 may promote circumferential acceleration of the second flow of fuel d102 through the second fuel circuit d112 such as to promote atomization of the fuel d102 when the fuel d102 egresses into the combustion chamber through the second fuel injection opening d125, thereby improving combustion performance, operability, and/or emissions outputs. In some embodiments, the vane structure d130 defines the swirl characteristic particularly for a flow of liquid fluid, such as liquid fuel, through the second circuit d112.

In one embodiment, the vane structure d130 includes two or more laterally separated rows of vanes through which fuel is provided. The plurality of vanes d130 in circumferential arrangement each define pin holes between each pair of vanes. In one embodiment, the vane structure d130 is configured to produce substantially no circumferential swirl of the fluid via the two or more laterally separated rows of vanes and pin holes. The vanes d130, and the pin holes defined therebetween, are circumferentially offset from one another, such that the openings between each pair of vanes d130 are laterally non-aligned between an upstream and downstream opening relative to the vane structure d130. In still various embodiments, the no-swirl vane structure d130 arrangement produces the no-swirl flow of the gaseous fluid, such as gaseous fuel, through the second circuit d112.

Referring now to FIG. 18, another cross sectional view of an exemplary embodiment of the fuel injector d100 is provided. Referring also to FIG. 19, a perspective view of the exemplary embodiment of the fuel injector d100 of FIG. 18 is provided. The embodiments depicted in regard to FIGS. 18 and 19 are configured substantially similarly as shown and described in regard to FIGS. 11 through 17. In FIGS. 18 and 19, the fuel injector d100 further includes an igniter d140 extended through an outlet port d105 through the downstream end d98 of the body d110. In various embodiments, the outlet port d105 is extended through the body d110 concentric to the reference centerline axis d13. The igniter d140 may be extended through a cavity d133 radially or concentrically inward of the fuel circuits d111, d112 and extended laterally within the body d110. In particular embodiments, the igniter d140 may extend through the cavity d133 from the upstream end d99 of the body d110 through an inlet port d108 to admit the igniter d140 into the cavity d133 and protrude from the downstream end d98 of the body d110 into a combustion chamber. The igniter d140 extends through the outlet port d105 such as to dispose the downstream end d98 of the igniter d140 to one or more of the flows of fuel d101, d102 egressed from their respective fuel circuits d111, d112.

In various embodiments, the igniter d140 provides an energy source to ignite and combust the flows of fuel d101, d102 egressed from their respective fuel circuits d111, d112. In one embodiment, the igniter d140 defines a glow plug such as to provide a source of thermal energy such that when one or more flows of fuel d101, d102 are exposed to heat generated from the igniter d140 causes the fuel d101, d102 to ignite. In particular embodiments, the second flow of fuel d102 defining a liquid fuel is exposed to heat generated from the igniter d140 to cause the fuel d102 to ignite.

A method for operation of the fuel injector d100 is provided herein in which a relatively low pressure second flow of fuel d102 is provided through a second fuel inlet opening d107 (FIGS. 11, 17, and 18) to the second fuel circuit d112. The relatively low pressure second flow of fuel d102 egresses from the body d110 of the fuel injector d100 via the second fuel injection opening d125. As the egressed fuel d102 flows closer to or touches the igniter d140, it is initially ignited (e.g., light-off) and may further ignite the first flow of fuel d101 egressed from the plurality of first fuel injection apertures d115. Following light-off, the pressure may increase such as to improve atomization and desirably alter combustion and heat release characteristics, such as to improve operability, performance, and reduce emissions output (e.g., smoke, unburned hydrocarbons, oxides of nitrogen, etc.).

The igniter d140 included through the body d110 of the fuel injector d100 may provide and/or improve providing dual fuel (i.e., the first and second flows of fuel d101, d102) operation of the fuel injector d100 at relatively small engine apparatuses, such as those for external or internal combustion engines, including those for automotive, personal or light water craft, or auxiliary power unit applications.

In still various embodiments, during operation of the fuel injector d100, the first flow of fuel d101 defining a gaseous fuel is provided through a first inlet opening d106 (FIGS. 11, 17, and 18) to the first fuel circuit d111. The fuel d101 egresses from the body d110 through the plurality of first fuel injection apertures d115 for combustion.

Referring now to FIG. 20, an exemplary embodiment of another portion of the fuel injector d100 is provided. The embodiment provided in regard to FIG. 20 is configured substantially similarly as shown and described in regard to FIGS. 11 through 19. In FIG. 20, the fuel injector d100 further includes a second plurality of apertures d115(a) disposed radially inward of the second fuel injection opening d125. In one embodiment, the second plurality of apertures d115(a) may be in fluid communication with the first fuel circuit d111 (FIG. 18) such as to allow another flow of gaseous fluid (depicted via arrows 101(a)) to egress through the second plurality of apertures d115(a). The first and second plurality of apertures d115, d115(a) may together provide flows of gaseous fuel d101 and fluid d101(a) radially inward and radially outward of the second flow of fuel d102. The combination of the flows of fuel d101 and fluid d101(a) radially surrounding the second flow of fuel d102 may desirably alter the projection, burn, and/or heat release characteristics of the second flow of fuel d102 in the combustion chamber. For example, during higher pressure operation of the second flow of fuel d102, the first flow of fuel d101 and fluid d101(a) may prevent or mitigate undesired liquid fuel build-up at the igniter d140, such as to prevent carbon build-up, degradation, or undesirable burning and production of emissions. As another example, the flow of fluid d101(a) radially inward of the second flow of fuel d102 may provide thermal attenuation (i.e., cooling) at the body d110 of the fuel injector d100 such as to desirably attenuate heat transfer to the second flow of fuel d102 to mitigate coking within the second fuel circuit d112.

In various embodiments, the flow of fluid d101(a) may define a portion of the first flow of fuel d101 from the first fuel circuit d111. In other embodiments, such as further described in regard to FIG. 21, the flow of fluid d101(a) may define air or an inert gas provided from the cavity d133, such as to provide thermal attenuation to portions of the fuel injector d100.

Referring now to FIG. 21, a cross sectional view of another exemplary embodiment of the fuel injector d100 is provided. The embodiment provided in regard to FIG. 21 is configured substantially similarly as shown and described in regard to FIGS. 11 through 20. In FIG. 21, the fuel injector d100 further includes a fluid inlet opening d185 providing fluid communication from the cavity d133 to a third circuit d113. The third circuit d113 is defined radially inward of the first circuit d111 and the second circuit d112. In various embodiments, the third circuit d113 is defined radially inward of the second circuit d112 at the downstream end d98 of the fuel injector d100. In one embodiment, the third circuit d113 is defined at the frusto-conical portion d117 of the fuel injector d100. The third circuit d113 is in fluid communication with the second plurality of apertures d115(a), such as depicted in FIG. 20. The fluid inlet opening d185 provides a flow of oxidizer (e.g., air) or inert gas, shown schematically via arrows d103, to egress from the cavity d133 through the second plurality of apertures d115(a) via the third circuit d113.

In various embodiments, a flow of fuel d101(a) (FIG. 20) may be provided from the first fuel circuit d111 to the third circuit d113. The flow of fluid d103 from the cavity d133 through the second plurality of apertures d115(a) via the third circuit d113 may improve fuel atomization as the flow of fluid d103 mixes with the flow of fuel d101(a) (FIG. 20). In one embodiment, the flow of fuel d101(a) may be a pilot fuel source from the second circuit d112. In another embodiment, the flow of fuel d101(a) provides a thermal and/or fluid break or barrier between the igniter d140 and portions of the fuel injector d100 radially outward of the igniter d140.

In another embodiment, the flow of fluid d103 from the cavity d133 through the second plurality of apertures d115(a) may provide a protective curtain or cooling film of fluid to mitigate deterioration or damage to the igniter d140 due to heat and pressure from burning the one or more flows of fuel d101, d102. For example, the flow of fluid d103 may egress from the second plurality of apertures d115(a) radially inward of the second flow of fuel d102 (FIG. 20) egressing the second fuel injection opening d125. The flow of fluid d103, such as depicted via the flow of fluid 101(a) in FIG. 20, provides a barrier or cooling film between the igniter d140 and the flows of fuel d101, d102 along with their subsequent burning and heat release.

Referring now to FIG. 22, another exemplary embodiment of the fuel injector d100 according to aspects of the present disclosure is provided. Regarding FIG. 22, the cavity d133 within the body d110 of the fuel injector d100 further defines an upstream cavity d133(a) and a downstream cavity d133(b) relative to a flow of fluid therethrough. Particularly, the upstream cavity 133(a) is defined at or upstream of a fuel injection opening d115(b) positioned in flow communication at the cavity 133. The downstream cavity d133(b) is generally defined downstream of the fuel injection opening d115(b).

In various embodiments, downstream cavity 133(b) defines a fuel/oxidizer premixing plenum at which flow of fuel d102 is mixed with flow of fluid 103 (e.g., an oxidizer). The fuel injection opening d115(b) is fluidly connected to the first fuel circuit d111, such as described above. In certain embodiments, the fuel injection opening d115(b) is positioned in axial or co-directional flow arrangement in the cavity d133 such as to provide a substantially axial or co-directional flow of fuel d101 through the fuel injection opening d115(b) to the flow of fluid d103 through the downstream cavity d133(b). The flow of fuel d102 and the flow of fluid d103 (e.g., oxidizer) is mixed at the downstream cavity d133(b) prior to egressing a premixed fuel/oxidizer mixture d101(b) through the plurality of fuel apertures d115 and/or d115(a) such as described above.

Referring now to FIG. 23 and FIG. 24, cross-sectional views are provided of the fuel injector d100 at respective planes B-B and planes A-A, such as sectioned in FIG. 22, FIG. 25, FIG. 26, and FIG. 27. The fuel injection opening d115(b) includes a plurality of discrete fuel injection openings d115(b) positioned in circumferential arrangement relative to centerline axis d13. As further provided above, the first fuel circuit d111 upstream of the fuel injection openings d115(b) is extended substantially annularly relative to the centerline axis d13 and then egresses the fuel d101 through the plurality of fuel injection openings d115(b).

In various embodiments, an inner body d110(a) of the body d110 of the fuel injector d100 fluidly segregates the cavity d133 (including, at least in part, upstream cavity d133(a) and downstream cavity d133(b)) from the first fuel circuit d111. In certain embodiments, a second inner body d110(b) is positioned radially inward of the body d110 such as to fluidly segregate the first fuel circuit d111 and the igniter d140.

Referring now to FIG. 25, it should be appreciated that certain embodiments of the fuel injector d100 may include a substantially solid inner body d110(a). Additionally, the fuel injector d100 may include at least a portion of the first fuel circuit d111 extended through the inner body d110(a).

Referring to FIG. 22 and FIG. 25, it should be appreciated that although embodiments of the fuel injector d100 are depicted having the fuel injection opening d115(b) extended from the first fuel circuit d111 extended through the inner body d110(a), other embodiments may include the fuel injection opening d115(b) extended from the first fuel circuit d111 extended from the outer or external body d110 surrounding the inner body d110(a).

Embodiments of the fuel injector d100 provided in regard to FIG. 22 and FIG. 25 may reduce undesired pressure losses related to providing relatively large masses or flowrates of oxidizer (e.g., fluid 103) for premixing with fuel (e.g., fuel 101) in relatively small premixing passages (e.g., downstream cavity d133(b). The momentum or velocity arising from ejecting the flow of fuel d101 through the fuel injection openings d115(b) in substantially axial or co-directional flow with the flow of fluid d103 allows for reduction in local pressure and reduction in pressure loss for the fluid d103 at the downstream cavity d133(b). The improved premixing at downstream cavity d133(b) prior to egressing the fuel/oxidizer mixture d101(b) to a combustion chamber (e.g., at d98) may reduce undesired emissions or particulates (e.g., oxides of nitrogen, carbon monoxide, carbon dioxide, smoke, soot, unburned hydrocarbons, etc.).

Referring now to FIG. 26 and FIG. 27, embodiments of the fuel injector d100 depicted may be configured substantially similarly as one or more of the embodiments described herein in regard to FIG. 11 through FIG. 25. In the embodiments generally depicted in FIG. 26 and FIG. 27, the fuel injector d100 further includes a flow control structure d150 positioned at the downstream cavity d133(b). The flow control structure d150 is extended circumferentially through the annular downstream cavity d133(b), such as depicted at the cross-sectional view in Plane C-C depicted in FIG. 28. The flow control structure d150 is configured to mitigate or eliminate risks associated with premature ignition of a fuel/oxidizer mixture (i.e., flashback or auto-ignition), such as within a fuel injector.

In certain embodiments, the flow control structure d150 includes a plurality of enlargements, recesses, projections, baffles, protrusions, vanes, or other structures configured to mitigate or discourage flow from the downstream end d98 toward the upstream end d99. In various embodiments, the flow control structure d150 allows for desired residence time for mixing the fuel d101 and fluid d103 at the downstream cavity d133(b) to form the fuel/oxidizer mixture d101(b). In still various embodiments, the flow control structure d150 desirably increases residence time by increasing the cross-sectional flow area and reducing bulk flow velocity of the fuel d101 and fluid d103. In a particular embodiment, the flow control structure d150 is a fluidic diode, such as a Tesla valve. In another particular embodiment, such as depicted in FIG. 27, the flow control structure d150 is a porous mesh.

Referring back to FIG. 19, in another embodiment, the flow of fluid d103 may additionally, or alternatively, egress via the outlet port d105 through which the igniter d140 is extended. The flow of fluid d103 may provide a protective curtain or cooling film such as described in regard to FIGS. 20 and 21.

Referring back to FIGS. 11 and 16 through 19, the fuel injector d100 further includes a fastening port d109 extended along the lateral direction L and co-directional to the reference centerline axis d13. The fastening port d109 is extended through a portion of the body d110 such as to provide a mechanical fastener (e.g., bolt, screw, tie rod, rod, etc.) to extend therethrough to fix the fuel injector d100 in place. In various embodiments, the fastening port d109 is configured to dispose the reference centerline axis d13 of the fuel injector d100 co-axial to a reference centerline of a combustion chamber. As such, the fastening port d109 may dispose the first and second fuel circuits d111, d112 substantially co-directional to a flow of combustion gases through a combustion chamber. The generally co-axial and co-directional disposition of the fuel injector d100 relative to a combustion chamber may reduce or eliminate turns, pressure drops, or other impedances to providing the flows of fuel d101, d102 through the fuel circuits d111, d112 and egress to the combustion chamber via the respective plurality of fuel apertures d115 and fuel injection opening d125.

In various embodiments, such as further depicted in regard to FIGS. 16, 19, and 21, a plurality of threads may be defined at an outside surface of the cylindrical portion d116 of the body d110. The cylindrical portion d116 defining a plurality of threads provides threading the fuel injector d100 into an engine apparatus, or portion thereof (e.g., heater body c100), to dispose the downstream end d98 at a combustion chamber, such as combustion chamber c102. A fastener at the fastening port d109 may further act as a mechanism to retain the lateral position (i.e., along the lateral direction L) of the fuel injector d100 relative to a surrounding engine apparatus.

Embodiments of the fuel injector d100 shown and depicted herein in regard to FIGS. 11 through 28 may be constructed via one or more manufacturing processes known in the art. In various embodiments, the fuel injector d100 may be constructed as a single, unitary construction. In another embodiment, the body d110 may be constructed as a single, unitary construction separate from the igniter d140. Manufacturing processes for constructing the fuel injector d100 may include one or more processes generally referred to as additive manufacturing or 3D printing. Additionally, or alternatively, manufacturing processes for constructing the fuel injector d100 may include one or more machining processes or other material removal processes, material additive processes such as welding, brazing, soldering, or bonding processes generally, or one or more casting or forming processes.

In still various embodiments, the fuel injector d100 may include one or more materials appropriate for fuel injection to a combustion chamber, such as, but not limited to, iron or iron-based materials, aluminum, magnesium, nickel, titanium, ceramic or metal matrix composites, or alloys or combinations thereof, or other materials appropriate for combustion systems. Furthermore, the fuel injector d100 may include one or materials appropriate for heat engines generally, or external or internal combustion engines, closed-cycle engines, Stirling cycle, Rankine cycle, or Brayton cycle machines more specifically.

Embodiments of the fuel injector d100 provided herein may be configured to receive and desirably inject a plurality of types of fuels through the first circuit d111 and the second circuit d112. Exemplary fuels include, but are not limited to, propane, ethane, coke oven gas, natural gas, synthesis gas, liquid fuel such as diesel fuel, gasoline, synthetic fuel, or a plurality of specifications of kerosene or jet fuel (e.g., Jet A, JP-8, etc.), or mixtures of gaseous and/or liquid fuels thereof.

A method for operation of the fuel injector d100 provides for selectively relatively low pressure/flow output and high pressure/flow output of fuel through each circuit d111, d112, d113 of the fuel injector d100. The fuel injector d100 provides for a relatively low pressure/flow operation of the fuel injector d100 for a first flow of fuel to egress from the fuel injector d100 and touch the hot igniter d140, such as defining glow plug, to ignite the fuel. The fuel injector d100 further provides for a relatively high pressure/flow operation of the fuel injector d100 for the first flow of fuel, or additionally or alternatively, a second flow of fuel, to egress the fuel injector d100 such as to avoid touching the igniter d140. As such, the relatively high pressure/flow operation of the fuel injector d100 prevents undesired burn-up, wear, or other deterioration of the igniter d140. The high pressure/flow operation of the fuel injector d100 may additionally, or alternatively, provide the second flow of fuel (e.g., via the second circuit d112) to generate a buffer, such as a fluid and/or thermal break, between the first flow of fuel from the first circuit d111 and the igniter d140. In still various embodiments, the first flow of fuel from the first circuit d111 defines a liquid fuel. The second flow of fuel from the second circuit d112 may define a liquid and/or gaseous fuel. In still other embodiments, one or more other fluids, such as a non-fuel fluid, may be provided through the first circuit d111, the second circuit d112, and/or the third circuit d113. In one embodiment, the fluid provided through the fuel injector d100 includes an inert gas, urea, or other substance such as to desirably control emissions, provide a thermal or fluid barrier, or clean one or more circuits or passages of the fuel injector d100. For example, urea may be added to the fuel such as to decrease emissions associated with diesel fuels or similar.

In still various embodiments, the fuel injector d100 provides a structure and method for operation at which the vane structure d130 provides or generating a circumferential swirl to the fuel through second circuit d112, such as described herein. In one embodiment, the method for operation includes providing a circumferential swirl to a liquid fluid or fuel via the vane structure d130 within the second circuit d112. The liquid fuel then egresses the fuel injector d100 via the respective opening(s) with at least a partial circumferential velocity component, such as depicted in regard to FIG. 11.

In another embodiment, the structure and method for operation includes providing or generating a substantially no-swirl or axial flow of fuel through the second circuit d112 via the vane structure d130 such as described herein. In one embodiment, the method for operation includes providing the gaseous fluid or fuel through a first upstream vane structure d130 relative to a second downstream vane structure d130. The second downstream vane structure d130 defines at least one opening circumferentially offset from an opening defined at the first upstream vane structure d130. In one embodiment, the method may include providing a single opening at the first upstream vane structure d130 and a single opening at the second downstream vane structure d130. The vane structure d130 may further provide for retarding a circumferential flow component of the fluid via the circumferentially offset opening defined at each vane structure d130. The method may further include egressing the flow of fuel via respective opening(s) with a substantially no-swirl or non-circumferential flow component. The substantially non-swirl flow of gaseous fluid may provide improved thermal and/or fluid barrier between the igniter d140 and the combustion gases radially or concentrically outward or surrounding the igniter d140.

Embodiments of the fuel injector d100 provided herein may provide relatively low pressure supply of the fuels d101, d102 through the fuel injector d100 for egress through the plurality of first fuel injection apertures d115 and second fuel injection opening d125 and combustion at a combustion chamber. In one embodiment, the fuel injector d100 provided herein may provide the second flow of fuel d102 defining a liquid fuel to be provided through the fuel injector d100 without a fuel pump. For example, the fuel injector d100 may receive the second flow of fuel d102 via header pressure from a fuel tank providing the second flow of fuel d102. Generally, as the fuel injector d100 provided herein may operate with relatively low pressure fuel sources, dual-fuel fuel injectors d100 may be provided to apparatuses typically too small or compact for dual-fuel systems, such as, but not limited to, external or internal combustion engines for automotive vehicles, personal or commercial marine vehicles, personal watercraft, light aircraft, including short takeoff and vertical landing (STOVL) vehicles, rotary or fixed wing aircraft, or auxiliary power units.

Now referring to FIGS. 29, and 30A, and 30B, exemplary heat exchanger bodies c600 (e.g., hot-side heat exchanger bodies c600) will be described. The presently disclosed hot-side heat exchanger bodies c600 may define part of a heater body c100 and/or a closed-cycle engine c002. For example, a hot-side heat exchanger body c600 may define at least a portion of a monolithic body or a monolithic body-segment. Such monolithic body or monolithic body-segment may define at least a portion of the heater body c100 and/or the closed-cycle engine c002. Additionally, or in the alternative, the presently disclosed hot-side heat exchanger bodies c600 may be provided as a separate component, whether for use in connection with a heater body c100, a closed-cycle engine c002, or any other setting whether related or unrelated to a heater body c100 or a closed-cycle engine c002. At least a portion of the hot-side heat exchanger body c600 may define a hot-side heat exchanger c106. While the heater bodies c100 depicted in the figures may show one hot-side heat exchanger body c600 and/or one hot-side heat exchanger c106, it will be appreciated that a heater body c100 may include a plurality of hot-side heat exchanger bodies c600 and/or a plurality of hot-side heat exchangers c106. For example, a heater body c100 may include one or more hot-side heat exchanger bodies c600, and/or a hot-side heat exchanger body c600 may include one or more hot-side heat exchangers c106.

As shown, a hot-side heat exchanger body c600 and/or a hot-side heat exchanger c106 may include a plurality of heating walls c616. The plurality of heating wall c616 may be configured and arranged as an array of heating walls c616. The heating walls c616 may be radially or concentrically adjacent to one another. The heating walls c616 may be configured and arranged as a spiral or a spiral arc, and may be disposed annularly or semi-annularly relative to the combustion chamber c102 and/or the longitudinal axis c204 thereof. The heating wall c616 may be concentrically nested with one another. The heating wall c616 may be configured and arranged as an array of substantially concentric spirals and/or an array of substantially concentric spiral arcs. By way of example, a spiral or spiral arc, such as in an array of substantially concentric spirals or spiral arcs, may correspond to at least a portion of an Archimedean spiral, a Cornu spiral, a Fermat's spiral, a hyperbolic spiral, a logarithmic spiral, a Fibonacchi spiral, an involute, or a squircular spiral, as well as combinations of these.

The heating walls c616 define a plurality of heating fluid pathways c602. The heating fluid pathways c602 may make up a portion of the hot-side heat exchanger body c600 and/or a hot-side heat exchanger c106, defining a pathway through which a heating fluid such as circulating combustion gas may flow. The heating fluid pathways c602 may fluidly communicate with an inlet plenum c604. The inlet plenum may include a combustion chamber c602. The heating fluid pathways c602 may be configured and arranged as an array of heating fluid pathways c602. The heating fluid pathways c602 may be radially or concentrically adjacent to one another with a heating wall c616 disposed between respective adjacent heating fluid pathways c602. The heating walls c616 may be radially or concentrically adjacent to one another with a heating fluid pathway c602 disposed between respective adjacent heating walls c616. The heating walls c616 may be configured and arranged as a spiral or a spiral arc, and may be disposed annularly or semi-annularly relative to the combustion chamber c102 and/or the longitudinal axis c204 thereof. The heating fluid pathways c602 may be concentrically nested with one another. The heating fluid pathways c602 may be configured and arranged as an array of substantially concentric spirals and/or an array of substantially concentric spiral arcs. The hot-side heat exchanger body c600 may include an array of alternating heating walls c616 and heating fluid pathways c602.

Upstream ends of the heating walls c616 may be circumferentially spaced about an inlet plenum c604, such as a combustion chamber. Upstream ends of the heating fluid pathways c602 may respectively define an inlet c606, which may be circumferentially spaced about the inlet plenum c604, such as the combustion chamber c102. At least some of the inlets c606 may be oriented oblique to the inlet plenum c604. At least some of the plurality of heating fluid pathways c602 may define a spiral pathway.

The inlet plenum c604, such as the combustion chamber c102, may fluidly communicate with the plurality of heating fluid pathways c602. The plurality of heating fluid pathways c604 may respectively define an inlet c606 circumferentially spaced about the inlet plenum c604 (and/or disposed radially about the inlet plenum c604). Respective ones of the plurality of heating fluid pathways c604 may define respective ones of a plurality of inlets c606. The plurality of inlets c604 may be circumferentially spaced about the inlet plenum c604 (and/or disposed radially about the inlet plenum c604). For example, the plurality of inlets c604 may be circumferentially spaced about the combustion chamber c102 (and/or disposed radially about the combustion chamber c102). In some embodiments, respective ones of the plurality of inlets may define respective ones of a plurality of combustion chamber outlets c412. Additionally, or in the alternative, the inlet plenum c604 may define a plurality of inlets c606 fluidly communicating with respective ones of the plurality of heating fluid pathways c602. For example, the combustion chamber c102 may define a plurality of combustion chamber outlets c412 and/or a plurality of inlets c606 fluidly communicating with respective ones of the plurality of heating fluid pathways c602.

The plurality of heating fluid pathways c602 may additionally or alternatively fluidly communicate with one or more outlet plenum c608, such as a recirculation annulus c208. The fluid communication between the plurality of heating fluid pathways c602 and the one or more outlet plenum c608, such as a recirculation annulus c208 may be at a downstream portion of respective ones of the plurality of heating fluid pathways c602. The outlet plenum c608 or recirculation annulus c208 may circumferentially surround at least a portion of the hot-side heat exchanger body c600 and/or the hot-side heat exchanger c106. For example, the outlet plenum c608 or recirculation annulus c208 may circumferentially surround at least a portion of the plurality of heating fluid pathways c602.

As shown, for example, in FIG. 29, the hot-side heat exchanger body c600 and/or a working-fluid body c108 may define a plurality of heat transfer regions c612. The plurality of heat transfer regions c612 may correspond to respective portions of a working-fluid body c108. A respective heat transfer region c612 may encompass a portion of the hot-side heat exchanger body c600 and/or a portion of the working-fluid body c108. Respective ones of the plurality of heat transfer regions c612 have a thermally conductive relationship with a corresponding portion c614 of the plurality of heating fluid pathways c602, such as a semiannular portion c614 of the plurality of heating fluid pathways c602. Respective ones of the plurality of heat transfer regions c612 may include a heat input region, at least one heat extraction region, and a plurality of working-fluid pathways c110. The heat input region may include a piston body c700 and the heat extraction region may include a regenerator body c800.

In some embodiments, a heat transfer region c612 may include at last a portion of a working-fluid body c108. For example, a heat transfer region c612 may include at least a portion of a piston body c700 and/or at least a portion of a regenerator body c800. Additionally, or in the alternative, a heat transfer region c612 include one or more working-fluid pathways c110 that have a thermally conductive relationship with a corresponding portion c614 (e.g., a semiannular portion) of at least some of the plurality of heating fluid pathways c602. For example, the heat transfer region c612 may include one or more working-fluid pathways c110 defined at least in part within a corresponding one or more heating wall c616 of a hot-side heat exchanger c106. Such working-fluid pathways c110 may define a pathway for an engine-working fluid to flow through the hot-side heat exchanger c106, such as through the one or more heating walls c616 thereof. Where a working-fluid pathway c110 flows through a hot-side heat exchanger c106, the heat transfer region c612 may include a portion of the working-fluid pathway within or defined by the hot-side heat exchanger c106, such as within a region of one or more heating wall c616 of the hot-side heat exchanger c106 corresponding to the heat transfer region c612.

The hot-side heat exchanger body c600 may include a plurality of working-fluid pathways c110 monolithically formed within the plurality of heating walls c616. The plurality of working-fluid pathways may be grouped into an array of working-fluid pathways c110 and/or a plurality of arrays of working fluid-pathways c110. An array of working-fluid pathways c110 may define a heat transfer region c612. A plurality of arrays of working-fluid pathways c110 may define a corresponding plurality of heat transfer regions c612. Respective ones of the plurality of arrays of working-fluid pathways c110 may be circumferentially spaced about the hot-side heat exchanger body c600. Respective ones of the plurality of heat transfer regions c600 may be circumferentially spaced about the hot-side heat exchanger body c600.

As shown, for example, in FIG. 29, at least some of the working-fluid pathways c110 may be radially or concentrically adjacent to one another. Additionally, or in the alternative, as also shown, at least some of the working-fluid pathways c110 may be semiannular to one another. The working-fluid pathways c110 may fluidly communicate between the heat input region and the at least one heat extraction region. The plurality of heating fluid pathways c602 may be disposed radially or concentrically adjacent to corresponding respective ones of the plurality of working-fluid pathways c110, such as radially or concentrically adjacent to respective ones of a plurality of semiannular working-fluid pathways c110. Respective ones of the plurality of heating fluid pathways c602 may have a thermally conductive relationship with corresponding respective ones of the plurality of working-fluid pathways c110.

The plurality of heat transfer regions c612 may be circumferentially spaced about the hot-side heat exchanger body c600. The semiannular portion c614 of the plurality of heating fluid pathways c602 corresponding to a respective heat transfer region c612 may correspond to a radial position of the respective heat transfer region c612. For example, the plurality of heating fluid pathways c602 may define a spiral pathway, spiraling annularly or semi-annularly around a longitudinal axis, A, c214. The portion c614 of the plurality of heading fluid pathways c602 passing the radial position of a respective heat transfer region c612 may define the semiannular portion c614 of the plurality of heating fluid pathways c602 corresponding to the respective heat transfer region c612.

In some embodiments, the plurality of heating fluid pathways c602 may pass adjacent to at least some of the plurality of heat transfer regions c612 in circumferential series. For example, the plurality of heating fluid pathways c602 may have a thermally conductive relationship with the at least some of the plurality of heat transfer regions c612, and the particular heat transfer region c612 with which a respective portion c614 of the plurality of heating fluid pathways c604 has a thermally conductive relationship may transition radially from one heat transfer region c612 to and adjacent heat transfer region c612. The circumferential series of a respective one of the plurality of heating fluid pathways c602 may have a sequence depending at least in part on a circumferential location of an inlet c606 to the respective one of the plurality of heating fluid pathways c602.

By way of example, a first heating fluid pathway c618 may pass adjacent to at least some of the plurality of heat transfer regions c612 in a first circumferential series that includes a first heat transfer region c620 followed by a second heat transfer region c622. The first circumferential series may additionally or alternatively include the second heat transfer region c622 followed by a third heat transfer region c624 and/or a fourth heat transfer region c626. For example, the fourth heat transfer region c626 may be preceded by the third heat transfer region c624. A second heating fluid pathway c628 may pass adjacent to at least some of the plurality of heat transfer regions c612 in a second circumferential series. The second circumferential series may include the second heat transfer region c622 followed by the third heat transfer region c624. The second circumferential series may additionally or alternatively include the third heat transfer region c624 followed by the fourth heat transfer region c626 and/or the first heat transfer region c620. For example, the first heat transfer region c620 may be preceded by the fourth heat transfer region c626. A third heating fluid pathway c630 may pass adjacent to at least some of the plurality of heat transfer regions c612 in a third circumferential series. The third circumferential series may include the third heat transfer region c624 followed by the fourth heat transfer region c626. The third circumferential series may additionally or alternatively include the fourth heat transfer region c626 followed by the first heat transfer region c620 and/or the second heat transfer region c622. For example, the second heat transfer region c622 may be preceded by the first heat transfer region c620. A fourth heating fluid pathway c632 may pass adjacent to at least some of the plurality of heat transfer regions c612 in a fourth circumferential series. The fourth circumferential series may include the fourth heat transfer region c626 followed by the first heat transfer region c620. The fourth circumferential series may additionally or alternatively include the first heat transfer region c620 followed by the second heat transfer region c622 and/or the third heat transfer region c624. For example, the third heat transfer region c624 may be preceded by the second heat transfer region c622.

During operation, heating fluid such as combustion gas flowing through the plurality of heating fluid pathways c602 may transfer heat to any one or more of the plurality of heat transfer regions c612. The rate or quantity of heat transferring from the heating fluid to a heat transfer region c612 may vary as between respective ones of the heat transfer pathways c602 and/or as between respective ones of the heat transfer regions c612. For example, the rate or quantity of heat transferring from the heating fluid to a heat transfer region c612 may depend at least in part on a temperature gradient between the heating fluid and the heat transfer region, such as a temperature gradient between the heating fluid and the engine-working fluid. In some embodiments, however, the heating fluid within the plurality of heating fluid pathways c602 may exhibit a temperature that differs as between at least two portion c614 (e.g., at least two semiannular portion) corresponding to respective heat transfer regions c612 and/or as between at least two heating fluid pathways c602 within a given portion c614 (e.g., within a semiannular portion) corresponding to a given heat transfer regions c612. Additionally, or in the alternative, the plurality of heat transfer regions c612 may exhibit a temperature that differs as between at least two heat transfer regions c612. For example, the engine-working fluid within the plurality of working-fluid pathways c110 corresponding to respective ones of the heat transfer regions c612 may exhibit a temperature that differ as between at least two heat transfer regions c612 and/or as between at least two working-fluid pathways c110 within a given heat transfer region c612.

In some embodiments, the temperature of a heating fluid such as a combustion gas may decrease as the heating fluid flows through the plurality of heating fluid pathways c602 and heat transfers from the heating fluid to the heat transfer regions c612 of the working-fluid body c108, such as from the heating fluid to engine-working fluid in the working-fluid pathways c110. However, with the plurality of heating fluid pathways c602 defining a spiral pathway, as shown for example in FIG. 29, respective ones of the plurality of heating fluid pathways c602 may encounter the respective ones of the plurality of heat transfer regions c612 in a differing sequence, which may depend at least in part on a circumferential location of an inlet c606 to the respective one of the plurality of heating fluid pathways c602.

For example, a first heating fluid pathway c618 may initially encounter the first heat transfer region c620, such as according to a first circumferential series, while a second heating fluid pathway c628 may encounter the first heat transfer region c620 last, such as according to a second circumferential series. Additionally, or in the alternative, a third heating fluid pathway c630 may encounter the first heat transfer region c620 third in series, such as according to a third circumferential series, and/or a fourth heating fluid pathway c632 may encounter the first heat transfer region c620 second in series, such as according to a fourth circumferential series.

As another example, the second heat transfer region c622 may have a thermally conductive relationship with the first heating fluid pathway c618 occurring second, such as according to the first circumferential series. The second heat transfer region c622 may have a thermally conductive relationship with the second heating fluid pathway c628 occurring first, such as according to the second circumferential series. The second heat transfer region c622 may have a thermally conductive relationship with the third heating fluid pathway c630 occurring last, such as according to the third circumferential series. The second heat transfer region c622 may have a thermally conductive relationship with the fourth heating fluid pathway c632 occurring third, such as according to the third circumferential series.

In some embodiments, a heat transfer region c622 may include a piston body c700 and/or a regenerator body c800, and/or a plurality of working-fluid pathways c110 fluidly communicating between the piston body c700 and/or the regenerator body c800. When a closed-cycle engine c002 includes a plurality of piston bodies, the piston assemblies may have a staggered or offset stroke cycle, such that a first piston and a second piston may be located at different points in respective stroke cycles upon least one point of the stroke cycle. For example, the first piston may be at a top point of the stroke cycle and the second piston may be at a bottom point of the stroke cycle. As another example, the first piston may be at a midpoint of the stroke cycle and the second piston may be at the top point or the bottom point of the stroke cycle. In some embodiments, engine-working fluid flowing from a piston body c700 (e.g., from a piston chamber c112) to a regenerator body c800 may exhibit a temperature that differs from engine-working fluid flowing in the opposite direction, from the regenerator body c800 to the piston body c700 (e.g., to the piston chamber c112).

The engine-working fluid flowing through the working-fluid pathways c110 may exhibit a temperature that depends at least in part on whether the engine-working fluid is flowing towards the regenerator body c800 (e.g., from the piston body c700) or towards the piston body c700 (e.g., from the regenerator body c800). For example, the temperature of the engine-working fluid may exhibit a first temperature when flowing towards the regenerator body c800 (e.g., from the piston body c700) and a second temperature when flowing towards the piston body c700 (e.g., from the regenerator body c800). In some embodiments the first temperature may be greater than the second temperature.

In some embodiments, the heating fluid such as combustion gas and the engine-working fluid may exhibit a temperature gradient that depends at least in part on whether the engine-working fluid is flowing towards the regenerator body c800 (e.g., from the piston body c700) or towards the piston body c700 (e.g., from the regenerator body c800). For example, a first temperature gradient may correspond to engine-working fluid flowing towards the regenerator body c800 (e.g., from the piston body c700) and a second temperature gradient may correspond to engine-working fluid flowing towards the piston body c700 (e.g., from the regenerator body c800). In some embodiments the first temperature gradient may be smaller than the second temperature gradient. In some embodiments the second temperature gradient may be greater than the first temperature gradient. For example, the first temperature gradient may be smaller than the second temperature gradient at least in part because of the temperature of the engine-working fluid flowing towards the regenerator body c800 (e.g., from the piston body c700) being greater than the temperature of engine-working fluid flowing towards the piston body c700 (e.g., from the regenerator body c800).

In some embodiments, the rate and/or quantity of heat transfer from the heating fluid to the engine-working fluid may depend on whether the engine-working fluid is flowing towards the regenerator body c800 (e.g., from the piston body c700) or towards the piston body c700 (e.g., from the regenerator body c800). For example, a first rate and/or quantity of heat transfer from the heating fluid to the engine-working fluid may correspond to engine-working fluid flowing towards the regenerator body c800 (e.g., from the piston body c700) and a second rate and/or quantity of heat transfer from the heating fluid to the engine-working fluid may correspond to engine-working fluid flowing towards the piston body c700 (e.g., from the regenerator body c800). In some embodiments the first rate and/or quantity of heat transfer may be smaller than the second rate and/or quantity of heat transfer. In other words, the second rate and/or quantity of heat transfer may be greater than the first rate and/or quantity of heat transfer. For example, the first rate and/or quantity of heat transfer may be smaller than the second rate and/or quantity of heat transfer at least in part because of the first temperature gradient corresponding to engine-working fluid flowing towards the regenerator body c800 (e.g., from the piston body c700) being smaller than the second temperature gradient corresponding to engine-working fluid flowing towards the piston body c700 (e.g., from the regenerator body c800).

In some embodiments, the heating efficiency of the heater body c100 may be enhanced at least in part by the second rate and/or quantity of heat transfer corresponding to engine-working fluid flowing towards the piston body c700 (e.g., from the regenerator body c800) being greater than the first rate and/or quantity of heat transfer corresponding to engine-working fluid flowing towards the regenerator body c800 (e.g., from the piston body c700). For example, in this way, a relatively larger proportion of the heat input by the heater body c100 may be applied to the engine-working fluid as the engine-working fluid flows towards the piston body c700 and thereby drives the piston downward, performing the downstroke portion of a stroke cycle. The heat input to the engine-working fluid during the downstroke may contribute to the downstroke (e.g., directly) by further heating and thereby further expanding the engine-working fluid. During the upstroke portion of the stroke cycle, a relatively smaller proportion of the heat input by the heater body c100 may be applied to the engine-working fluid, which may reduce or mitigate a potential for heat input to the engine-working fluid to counteract the upstroke by further heating and thereby expanding the engine-working fluid, providing an additional or alternative efficiency enhancement. With a relatively smaller proportion of the heat input by the heater body c100 applied to the engine-working fluid during the upstroke, a smaller portion of the heat input may be transferred to the regenerator body c800. While the regenerator body c800 may be configured to retain heat, at least some heat transferring to the regenerator body c800 may be lost. By transferring a larger proportion of the heat input of the heater body c100 to the engine-working fluid when flowing towards the piston body c700 (e.g., from the regenerator body c800), less heat energy may be lost to the regenerator body c800, thereby providing yet another additional or alternative efficiency enhancement.

In some embodiments, at least a portion of the heater body c100 (e.g., the hot-side heat exchanger body c600 and/or the working-fluid body c108) may be configured such that the temperature gradient between the temperature gradient between the heating fluid and the engine-working fluid is relatively small when the engine-working fluid is flowing towards the regenerator body c800. For example, the temperature gradient between the heating fluid and the engine-working fluid may be minimal when the engine-working fluid is flowing towards the regenerator body c800. With a relatively small and/or minimal temperature gradient, the rate and/or quantity of heat transfer to the engine-working fluid when flowing towards the regenerator body c800 may be minimal or nominal. Additionally, or in the alternative, at least a portion of the heater body c100 (e.g., the hot-side heat exchanger body c600 and/or the working-fluid body c108) may be configured such that the temperature gradient between the temperature gradient between the heating fluid and the engine-working fluid is relatively large when the engine-working fluid is flowing towards the piston body c700. For example, the temperature gradient between the heating fluid and the engine-working fluid may be maximal when the engine-working fluid is flowing towards the piston body c700. With a relatively large and/or maximal temperature gradient, the rate and/or quantity of heat transfer to the engine-working fluid when flowing towards the regenerator body c800 may be maximized.

In some embodiments, the rate and/or quantity of heat transferred from the heating fluid to the engine-working fluid may exhibit a ratio of heat transfer when flowing towards the piston body c700 to heat transfer when flowing towards the regenerator body c800 of from about 1:1 to about 100:1, such as from about 2:1 to about 100:1, such as from about 2:1 to about 10:1, such as from about 10:1 to about 20:1, such as from about 20:1 to about 50:1, or such as from about 50:1 to about 100:1. The ratio may be at least 1:1, such as at least 2:1, such as at least 10:1, such as at least 20:1, such as at least 50:1, or such as at least 90:1. The ratio may be less than 100:1, such as less than 90:1, such as less than 50:1, such as less than 20:1, such as less than 10:1, or such as less than 2:1.

As the heating fluid flows through the plurality of heating fluid pathways c602, heat may preferentially transfer to heat transfer regions c612 where the temperature gradient is larger or largest, thereby preferentially providing heat to the heat transfer regions where heat is needed more or most, for example, in favor of other heat transfer regions c612 with a lower or lowest temperature gradient. In some embodiments, heat may preferentially transfer to heat transfer regions (e.g., to engine-working fluid flowing through working-fluid pathways c110 therein) corresponding to a piston during a downstroke portion of the stroke cycle relative to heat transfer regions corresponding to a piston during an upstroke portion of the stoke cycle. Such preferential heat transfer may be accomplished at least in part by providing a relatively greater temperature gradient during the downstroke portion of the stroke cycle as described. With the plurality of heating fluid pathways c602 defining a spiral pathway, as shown for example in FIG. 29, the plurality of heating fluid pathways c602 may encounter all or a portion of the heat transfer regions c612, thereby allowing for preferential heat transfer to the heat transfer regions c612 where the temperature gradient is larger or largest.

In some embodiments, a hot-side heat exchanger body c600 may include a combustion chamber c102 disposed annularly about an axis c204. A hot-side heat exchanger body c600 may additionally include a conditioning conduit c122 circumferentially surrounding the combustion chamber c102. The conditioning conduit c122 may fluidly communicate with the combustion chamber c102 at a distal portion c202 of the combustion chamber c102.

In some embodiments, as shown for example in FIGS. 29, 30A, and 30B, a hot-side heat exchanger body c600 may include a plurality of combustion fins c450 circumferentially spaced about the perimeter of the combustion chamber c102 (and/or disposed radially about the perimeter of the combustion chamber c102). The plurality of combustion fins c450 may occupy a radially or concentrically inward portion of the hot-side heat exchanger body c600. In some embodiments, a portion of the hot-side heat exchanger body c600 may define a second combustion chamber c448. The second combustion chamber c448 may include a plurality of combustion fins c450 circumferentially spaced about the perimeter of the combustion chamber c102 (and/or disposed radially about the perimeter of the combustion chamber c102). The plurality of combustion fins c450 may define at least a portion of the plurality of heating fluid pathways c602. Additionally, or in the alternative, the plurality of combustion fins c450 may define a plurality of combustion-gas pathways c422 fluidly communicating upstream with the combustion chamber c102 and downstream with a corresponding plurality of heating fluid pathways c602. Such combustion-gas pathways c422 may concurrently define at least a portion of the second combustion chamber c448 and at least a portion of the plurality of heating fluid pathways c602. The second combustion chamber c448 may allow combustion to take place at an air-to-fuel ratio closer to the stoichiometric air-to-fuel ratio.

The plurality of combustion fins c450 may be monolithically integrated with corresponding ones of a plurality of heating walls c616 that respectively define the plurality of heating fluid pathways c602. Additionally, or in the alternative, the combustion fins c450 and the heating walls c616 may be spaced apart from one another, such as with a gap or pathway between an upstream end of the heating walls c602 and a downstream end of the combustion fins c450. The portion of a heating fluid pathways c602 defined by the combustion fins c450 may be referred to as combustion-gas pathways c422. The combustion-gas pathways c422 may at least partially occupy the region of the hot-side heat exchanger c106 where combustion is configured to occur. Combustion may occur in the combustion-gas pathways c42 at least in part by the combustion fins c450 being heated to a sufficiently high temperature during operation to prevent flame quenching.

The plurality of heating fluid pathways c602 may fluidly communicate with the outlet plenum c608 at a corresponding plurality of circumferential locations about the hot-side heat exchanger body c600. By way of example, a first heating fluid pathway c618 may fluidly communicate with an outlet plenum c608 at a first circumferential location c634 about a circumferential axis of the hot-side heat exchanger c106. The first circumferential location c634 may be from about 0 to 30 degrees about the circumferential axis, such as from about 0 to 15 degrees on the circumferential axis. A second heating fluid pathway c628 may fluidly communicate with an outlet plenum c608 at a second circumferential location c636 about the circumferential axis. The second circumferential location c636 may be from about 90 to 120 degrees about the circumferential axis, such as from about 90 to 105 degrees about the circumferential axis. A third heating fluid pathway c630 may fluidly communicate with an outlet plenum c608 at a third circumferential location c638 about the circumferential axis. The third circumferential location c638 may be from about 180 to 210 degrees about the circumferential axis, such as from about 180 to 195 degrees about the circumferential axis c205. A fourth heating fluid pathway c632 may fluidly communicate with an outlet plenum c608 at a fourth circumferential location c640 about the circumferential axis c205. The fourth circumferential location c640 may be from about 270 to 300 degrees about the circumferential axis c205, such as from about 270 to 285 degrees about the circumferential axis c205.

A hot-side heat exchanger body c600 and/or a working-fluid body c108 may define any number of heat transfer regions c612. For example, heat exchanger body c600 and/or a working-fluid body c108 may define from 1 to 10 heat transfer regions c612, such as from 2 to 8 heat transfer regions c612, such as from 3 to 5 heat transfer regions. A plurality of heat transfer regions c612 may be circumferentially spaced about the hot-side heat exchanger body, such as at respective circumferential regions about the circumferential axis c205. As shown, four heat transfer regions c612 may be circumferentially spaced about the hot-side heat exchanger body c600. By way of example, a first heat transfer region c620 may be disposed about a first circumferential segment or sector about the circumferential axis c205 of the hot-side heat exchanger c106. The first circumferential segment or sector may be from about 270 to about 360 degrees about the circumferential axis c205. A second heat transfer region c622 may be disposed about a second circumferential segment or sector about the circumferential axis c205. The second circumferential segment or sector may be from about 180 to about 270 degrees about the circumferential axis c205. A third heat transfer region c624 may be disposed about a third circumferential segment or sector about the circumferential axis c205. The third heat transfer region c624 may be from about 90 to about 180 degrees about the circumferential axis c205. A fourth heat transfer region c626 may be disposed about a fourth circumferential segment or sector about the circumferential axis c205. The fourth circumferential segment or sector may be from about 0 to about 90 degrees about the circumferential axis c205.

A hot-side heat exchanger body c600 and/or a hot-side heat exchanger c106 may include any number of heating fluid pathways c602. For example, a hot-side heat exchanger body c600 and/or a hot-side heat exchanger c106 may include from 1 to 96 heating fluid pathways c602, such as from 1 to 48 heating fluid pathways c602, such as from 4 to 32 heating fluid pathways c602, such as from 8 to 24 heating fluid pathways c602, such as from 12 to 20 heating fluid pathways c602, such as from 4 to 16 heating fluid pathways c602, such as from 4 to 8 heating fluid pathways c602, such as at least 4, at least 8, at least 16, or at least 32 heating fluid pathways c602.

In some embodiments, at least some of the plurality of heating fluid pathways c602 may have a substantially uniform cross-sectional width and/or a substantially uniform cross-sectional area. The substantially uniform cross-sectional width and/or a substantially uniform cross-sectional area of a heating fluid pathway c602 may be present along at least a portion of a length of the heating fluid pathway c602.

At least some of the heating fluid pathways c602 may define a spiral pathway spiraling annularly or semi-annularly around a longitudinal axis A 214. A spiral pathway may follow a spiral arc having any desired curvature. The spiral arc may continue along all or a portion of the spiral pathway defined by the heating fluid pathway c602. By way of example, a spiral and/or a spiral arc, such as in a spiral pathway, may correspond to at least a portion of an Archimedean spiral, a Cornu spiral, a Fermat's spiral, a hyperbolic spiral, a logarithmic spiral, a Fibonacchi spiral, an involute, or a squircular spiral, as well as combinations of these. As shown, in some embodiments the plurality of heating fluid pathways c602 may define a squircular spiral. At least a portion of a squircular spiral may include an arc corresponding to a squircle. The plurality of heating fluid pathways c602 may have an arc length of from 180 degrees to 1260 degrees, such as from 180 degrees to 450 degrees, such as from 315 degrees to 765 degrees, such as from 675 degrees to 1260 degrees.

In some embodiments, the plurality of heating fluid pathways c602 may include radially or concentrically adjacent pathways. Additionally, or in the alternative, the plurality of heating fluid pathways c602 may include one or more inverse pairs. For example, an inverse pair may include a pair of heating fluid pathways c602 fluidly communicating with the inlet plenum c604 (e.g., the combustion chamber c102) at opposite sides thereof. Additionally, or in the alternative, an inverse pair may include a pair of heating fluid pathways c602 fluidly communicating with the outlet plenum c608 (e.g., the recirculation annulus c208) at opposite sides thereof. By way of example, a first heating fluid pathway c618 and a third heating fluid pathway c630 may define an inverse pair. As another example, a second heating fluid pathway c628 and a fourth heating fluid pathway c632 may define an inverse pair. The inverse pair may follow a spiral arc having any desired curvature, such as a spiral arc inverse pair. For example, the heating fluid pathways c602 may define a plurality of spiral arc inverse pairs. In some embodiments, an inverse pair may include a parabolic spiral.

Now referring to FIGS. 30A and 30B, further exemplary embodiments of a hot-side heat exchanger body c600 will be described. As shown, in some embodiments, a hot-side heat exchanger body c600 may have a plurality of heating walls c616 and/or combustion fins c450 that respectively include a plurality of conduction breaks c605. The conduction breaks c605 may be disposed radially or concentrically outward relative to the plurality of combustion fins c450, and/or radially or concentrically inward relative to the plurality of heating walls c616. The conduction breaks c605 may at least partially inhibit heat conduction from the plurality of combustion fins c450 to the plurality of heating walls c616. The conduction breaks c605 may impart a decrease in thermal conductivity relative to the thermal conductivity of the plurality of heating walls c616 and/or the plurality of combustion fins c450. The plurality of heating walls c616 may be configured an arranged in a spiral array or spiral arc, such as an annular or semiannular spiral array or spiral arc. Additionally, or in the alternative, the plurality of combustion fins c450 may be configured an arranged in a spiral array or spiral arc, such as an annular or semiannular spiral array or spiral arc. A combustion fins c450 and a corresponding heating wall c616 may follow a common trajectory. Additionally, or in the alternative, one or more combustion fins c450 may be staggered or offset from one or more heating walls c616. The condition breaks c605 may be configured to reduce heat conduction along the plurality of heating walls c616, such as along a radial axis or a circumferential axis. For example, the conduction breaks c450 may reduce heat conduction from a downstream portion of the combustion fins c450 to an upstream portion of the heating walls c616, and/or from an upstream portion of the plurality of heating walls c616 to a downstream portion of the plurality of heating walls c616. During operation, the combustion fins c450 may operate at a relatively higher temperature at least in part because of the reduced heat conduction attributable to the conduction breaks.

In some embodiments, a portion of the heating wall c616 upstream from a conduction break c605 may define a combustion fin c450. Additionally, or in the alternative, at least a portion of the heating wall c616 downstream from a conduction break c605 may define a heat transfer fin c607. The plurality of heating walls c616 may be formed of one or more materials, and/or may exhibit one or more material properties and/or structures. For example, the heat transfer fins c607 and the combustion fins c450 may differ from one another in respect of material composition, material properties, and/or material structure. In some embodiments, the heat transfer fins c607 may exhibit a greater thermal conductivity relative to the combustion fins c450. Additionally, or in the alternative, the combustion fins c450 may exhibit a greater heat capacity relative to the heat transfer fins c607. A desired thermal conductivity and/or heat capacity may be imparted to the combustion fins c450 and/or the heat transfer fins c607 at least in part by augmenting the material properties and/or structure during additive manufacturing. For example, the density and/or porosity may be augmented by modifying additive manufacturing parameters to impart desired thermodynamic properties, such as heat capacity properties and/or thermal conductivity properties. Density and/or porosity may be augmented by modifying the degree of consolidation of powder material, and/or by providing regions of unsintered or partially sintered regions of powder material. Additionally, or in the alternative, material structure may be augmented to impart desired thermodynamic properties. For example, a lattice structure, a porous medium, a cellular structure, or the like may be provided to impart desired heat capacity properties and/or thermal conductivity properties to the combustion fins c450 and/or the heat transfer fins c607.

The plurality of condition breaks c605 may be disposed circumferentially adjacent to one another at the respective ones of the plurality of heating walls c616. The location of the conduction breaks c605 at the respective heating walls c616 may define a circumferential array of conduction breaks c605. A plurality of combustion fins c450 may occupy a radially or concentrically inward position of the hot-side heat exchanger body c600 relative to the circumferential array of conduction breaks c605. At least a portion of the plurality of heating walls c616 may define a corresponding plurality of heat transfer fins c607. The heat transfer fins c616 may occupy a radially or concentrically outward position of the hot-side heat exchanger body c600 relative to the circumferential array of conduction breaks c605. For example, the radially or concentrically outward portion of the heating walls c616 may define the heat transfer fins c607.

The plurality of combustion fins c450 may define a corresponding plurality of combustion-gas pathways c422. The plurality of combustion fins c450 and/or the plurality of combustion-gas pathways c422 may be configured an arranged in a spiral array, such as a semiannular spiral array. The plurality of combustion fins c450 may spiral concentrically outward from a combustion chamber outlet c412 towards the corresponding conduction break c605. The plurality of combustion fins c450 may be arranged in an array of annular or semiannular substantially concentric spirals and/or substantially concentric spiral arcs relative to the longitudinal axis c204. The circumferential array of conduction breaks c605 may define a radially or concentrically outward perimeter of the plurality of combustion fins c450.

The plurality of heat transfer fins c607 may define a corresponding plurality of heating fluid pathways c602. The plurality of heat transfer fins c607 and/or the plurality of heating fluid pathways c602 may be configured an arranged in a spiral array, such as an annular or semiannular spiral array. The plurality of heat transfer fins c607 may spiral concentrically outward from the corresponding conduction breaks, transecting respective ones of the plurality of heat transfer regions c612. The circumferential array of conduction breaks c605 may define a radially or concentrically inward perimeter of the plurality of heating walls c616. Additionally, or alternatively, the circumferential array of conduction breaks c605 may define a radially or concentrically inward perimeter of the plurality of heat transfer regions c612. For example, the plurality of working-fluid bodies c108 and/or the plurality of working-fluid pathways c110 may occupy a region of the hot-side heat exchanger body c600 disposed radially or concentrically outward from the circumferential array of conduction breaks c605. Additionally, or in the alternative, the portion of the heat transfer fins c607 and/or the heating walls c616 that include working-fluid pathways c110 monolithically defined therein may occupy a region of the hot-side heat exchanger body c600 disposed radially or concentrically outward from the circumferential array of conduction breaks c605.

The plurality of heat transfer regions c612 may respectively include an array of working-fluid pathways c110, such as a plurality of arrays of working fluid pathways c110. The array of working fluid pathways c110 may be monolithically defined within respective ones of the plurality of heating walls c616 (e.g., within respective ones of the plurality of heat transfer fins c607). The circumferential array of conduction breaks c605 may define a radially or concentrically inward perimeter of the plurality of working-fluid pathways c110. Respective ones of the plurality of arrays of working-fluid pathways c110 may be disposed circumferentially adjacent to one another about the hot-side heat exchanger body c600. Respective ones of the plurality of arrays of working-fluid pathways c110 may define at least a portion of a working-fluid body c108. A plurality of working-fluid bodies c108 may be disposed circumferentially adjacent to one another about the hot-side heat exchanger body c600. The circumferential array of conduction breaks c605 may define a radially or concentrically inward perimeter of the plurality of working-fluid bodies c108.

In some embodiments, at least a portion of fuel combustion may take place within the plurality of combustion-gas pathways c422. Combustion that takes place within the combustion-gas pathways c422 may be attributable at least in part to the reduced heat conduction along the heating walls c616 provided by the conduction breaks c605. In some embodiments, the conduction breaks c605 may prevent or reduce a possibility that combustion may quenching prematurely. During operation, the combustion fins c450 may reach a sufficiently high temperature for stable combustion to take place within the plurality of combustion-gas pathways c422 without being prematurely quenched, such as by conductive heat transfer along the heating walls c616 and into the working-fluid bodies c108. The reduction in heat conduction provided by the conduction breaks c605 may reduce the potential that heat transfer to the working fluid-pathways c610 may decrease the temperature of the heating walls c616 to a level that prematurely quenches combustion.

The conduction breaks c605 may allow the combustion fins to remain at a sufficiently high temperature to allow fuel combustion to approach complete combustion within the plurality of combustion-gas pathways c422. The circumferential array of conduction breaks c605 may be located at a distance along the combustion-gas pathways c422 selected to allow sufficient time for complete combustion upon the combustion gas having encountered the conduction breaks c605. In this way, the conduction breaks may provide for reduced emissions attributable to complete combustion and a corresponding reduction of unburnt combustion products in exhaust gas. The plurality of heat transfer regions c612 and/or the arrays of working-fluid pathways c110 may be located substantially immediately downstream from the circumferential array of conduction breaks c605, thereby allowing the hot combustion gas to begin heating the working fluid in the working-fluid pathways substantially immediately upon complete combustion.

As used herein, the term “complete combustion” refers to a state of fuel combustion that yields carbon dioxide and water as the combustion products with an absence of hydrocarbons. Complete combustion may yield carbon monoxide as a combustion product on the order of parts-per-million, such as single-digit parts-per-million (ppm). For example, with complete combustion, carbon monoxide may be present as a combustion product in an amount of less than 10 ppm, such as less than 5 ppm, or such as less than 1 ppm. In some embodiments, complete combustion may be qualitatively characterized by a blue flame, whereas incomplete combustion may be qualitatively characterized by an orange flame.

In some embodiments, a heater body c100 may be configured to burn fuel in a lean combustion environment. As mentioned, a lean combustion environment may be characterized by an equivalence ratio (i.e., the ratio of the actual fuel-to-air ratio to the stoichiometric fuel-to-air ratio), such as an equivalence ratio of from about 0.5 to about 1.0, such as from about 0.6 to about 0.9, or from about 0.7 to about 0.8. A lean combustion environment may generate a relatively longer flame length, which may otherwise point to a relatively larger combustion zone as an approach for reducing the potential for premature quenching and/or to allow for complete combustion.

In some embodiments, a heater body c100 configured to allow combustion to take place within the combustion-gas pathways c422 not only allows for complete combustion; but additionally, or in the alternative, a heater body c100 configured to allow fuel combustion within the plurality of combustion-gas pathways c422 may allow a heater body c100 to be operated at a higher equivalence ratio, thereby improving fuel efficiency and/or heating efficiency, while reducing emissions. Additionally, or in the alternative, the heater body c100 may be configured with a relatively smaller combustion chamber c102, thereby reducing material costs and weight.

In some embodiments, a combustion zone may occupy a position that includes the combustion-gas pathways c422. For example, the combustion-gas pathways c422 may define at least a portion of a second combustion zone c407 as described herein. The circumferential array of conduction breaks c605 may define a radially or concentrically outward perimeter of the second combustion zone c407. In some embodiments, the array of conduction breaks c605 may define an array of burner gaps c421. Such burner gaps may be configured as described herein. Additionally, or in the alternative, a hot-side heat exchanger body c600 may include both an array of conduction breaks c605 and an array of burner gaps c421.

The combustion fins c450 may be spatially separated from the heating walls c616 (e.g., the heat transfer fins c607), such that a conduction break c605 may include a physical gap or space defined by the spatial separation between a combustion fin c450 and heating wall c616 (e.g., a heat transfer fin c607). Additionally, or in the alternative, a conduction break c605 may include a change in a material property, a change in material composition, and/or a change in structure relative to the combustion fin c450 and/or the heat transfer fin c607 that provides a reduction in heat conduction relative to the combustion fin c450 and/or the heat transfer fin c607. For example, a conduction break c605 may include a structure such as a mesh, a three-dimensional lattice, a porous medium, or unsintered or partially sintered powder material, as well as combinations of these.

As shown in FIG. 30B, The plurality of heating walls c616 and/or combustion fins c450 may have a plurality of openings c451 (e.g., pore-like openings) that fluidly communicate with the plurality of combustion-gas pathways c422 of the hot-side heat exchanger c106 and define the hot-zone fuel injectors c413. In some embodiments, at least a portion of the hot-zone fuel pathways c415 may define a vaporization heat exchanger c417 that provides a heat transfer relationship between a combustion flame c426 and fuel within the hot-zone fuel pathways c415, and or between hot combustion gas c426 fuel within the hot-zone fuel pathways c415. The vaporization heat exchanger c417 may be effective to vaporize fuel (e.g., liquid fuel), such as when the fuel is within the hot-zone fuel pathways c415 and/or the hot-zone fuel injectors c413, or as the fuel is discharged from the openings (e.g., the pore-like openings) of the hot-zone fuel injectors c413.

Now referring to FIG. 31, exemplary methods of heating a plurality of heat transfer regions will be described. The exemplary methods of heating a plurality of heat transfer regions may include, for example, methods of heating one or more working-fluid bodies c108. For example, exemplary methods may be performed in connection with operation of a hot-side heat exchanger body c600, a working-fluid body c108, a heater body c100, and/or a closed-cycle engine c002 as described herein. As shown in FIG. 31, an exemplary method c650 may include, at block c652, flowing a first heat transfer fluid through a plurality of heating fluid pathways c602 fluidly communicating with an inlet plenum c604. Respective ones of the plurality of heating fluid pathways c602 may define a spiral pathway. The exemplary method c650 may include, at block c654, transferring heat from the first heat transfer fluid to a plurality of heat transfer regions c612. Respective ones of the plurality of heat transfer regions c612 may have a heat transfer relationship with a corresponding semiannular portion of the plurality of heating fluid pathways c602.

In some embodiments, transferring heat from the first heat transfer fluid to the plurality of heat transfer regions, at block 654, may include transferring heat from the plurality of heating fluid pathways c602 to at least some of the plurality of heat transfer regions c612 in circumferential series. The circumferential series of a respective one of the plurality of heating fluid pathways c612 may have a sequence depending at least in part on a circumferential location of an inlet c606 to the respective one of the plurality of heating fluid pathways c602.

Control systems and methods of controlling various systems disclosed herein will now be provided. A control system generates control commands that are provided to one or more controllable devices of the system. The controllable devices execute control actions in accordance with the control commands. Accordingly, the desired output of the system can be achieved.

FIG. 32 provides an example computing system in accordance with an example embodiment of the present disclosure. The one or more controllers, computing devices, or other control devices described herein can include various components and perform various functions of the one or more computing devices of the computing system b2000 described below.

As shown in FIG. 32, the computing system b2000 can include one or more computing device(s) b2002. The computing device(s) b2002 can include one or more processor(s) b2004 and one or more memory device(s) b2006. The one or more processor(s) b2004 can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and/or other suitable processing device. The one or more memory device(s) b2006 can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices.

The one or more memory device(s) b2006 can store information accessible by the one or more processor(s) b2004, including computer-readable instructions b2008 that can be executed by the one or more processor(s) b2004. The instructions b2008 can be any set of instructions that when executed by the one or more processor(s) b2004, cause the one or more processor(s) b2004 to perform operations. In some embodiments, the instructions b2008 can be executed by the one or more processor(s) b2004 to cause the one or more processor(s) b2004 to perform operations, such as any of the operations and functions for which the computing system b2000 and/or the computing device(s) b2002 are configured, such as e.g., operations for controlling certain aspects of power generation systems and/or controlling one or more closed cycle engines as described herein. For instance, the methods described herein can be implemented in whole or in part by the computing system b2000. Accordingly, the method can be at least partially a computer-implemented method such that at least some of the steps of the method are performed by one or more computing devices, such as the exemplary computing device(s) b2002 of the computing system b2000. The instructions b2008 can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the instructions b2008 can be executed in logically and/or virtually separate threads on processor(s) b2004. The memory device(s) b2006 can further store data b2010 that can be accessed by the processor(s) b2004. For example, the data b2010 can include models, databases, etc.

The computing device(s) b2002 can also include a network interface b2012 used to communicate, for example, with the other components of system (e.g., via a network). The network interface b2012 can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers b1510, antennas, and/or other suitable components. One or more controllable devices b1534 and other controllers b1510 can be configured to receive one or more commands or data from the computing device(s) b2002 or provide one or more commands or data to the computing device(s) b2002.

The technology discussed herein makes reference to computer-based systems and actions taken by and information sent to and from computer-based systems. One of ordinary skill in the art will recognize that the inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components. For instance, processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memory, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the present disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

This written description uses examples to describe the presently disclosed subject matter, including the best mode, and also to provide any person skilled in the art to practice the subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the presently disclosed subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A monolithic combustor body configured to provide multi-stage combustion, the combustor body comprising: a combustion chamber body disposed annularly about a longitudinal axis and defining a combustion chamber; and a heat exchanger having a plurality of heating walls comprising a heat sink, the plurality of heating walls occupying a radially or concentrically outward position relative to the combustion chamber and defining a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber; wherein during operation, the combustion chamber provides a vortex combustion pattern comprising a vortex flow field having a centripetal force that draws a combustion flame inward while propelling unburnt combustion gas outward, and the combustor body exhibits multi-stage combustion, the multi-stage combustion comprising: a first combustion zone occupying a distal or medial position of the combustion chamber relative to the longitudinal axis, wherein the first combustion zone occupies at least a portion of the vortex flow field; and a second combustion zone occupying a proximal position relative to the first combustion zone, and a radially or concentrically outward position relative to the longitudinal axis of the combustion chamber and a radially or concentrically inward position of the plurality of combustion-gas pathways defined by the plurality of heating walls of the heat exchanger; wherein during operation, the second combustion zone exhibits auto-ignition, wherein the first combustion zone exhibits a lean combustion environment prior to auto-ignition at the second combustion zone, and wherein upon auto-ignition at the second combustion zone, the first combustion zone transitions to a rich combustion environment and the second combustion zone thereafter exhibits a lean combustion environment.
 2. The monolithic combustor body of claim 1, wherein the second combustion zone occupies at least part of a proximal region of the combustion chamber.
 3. The monolithic combustor body of claim 1, wherein the heat sink comprises a plurality of working-fluid pathways, the plurality of working fluid pathways having a heat transfer relationship with the plurality of combustion-gas pathways.
 4. The monolithic combustor body of claim 3, wherein the plurality of heating walls comprise the plurality of working-fluid pathways monolithically formed within at least a portion of the plurality of heating walls.
 5. The monolithic combustor body of claim 1, comprising: a plurality of combustion fins circumferentially spaced about a perimeter of the combustion chamber, the plurality of combustion fins defining a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 6. The monolithic combustor body of claim 5, wherein the plurality of combustion fins define a portion of respective ones of the plurality of heating walls.
 7. The monolithic combustor body of claim 5, wherein the second combustion zone occupies at least part of the radially or concentrically inward portion of the plurality of combustion-gas pathways defined by the plurality of combustion fins.
 8. The monolithic combustor body of claim 5, wherein the plurality of combustion fins and/or the plurality of heating walls are configured to support auto-ignition at the second combustion zone when heated by combustion at the first combustion zone.
 9. The monolithic combustor body of claim 1, comprising: one or more fuel pathways monolithically integrated with a proximal portion of the combustion chamber body and/or a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 10. The monolithic combustor body of claim 9, comprising: a plurality of combustion fins circumferentially spaced about a perimeter of the combustion chamber, the plurality of combustion fins defining a radially or concentrically inward portion of the plurality of combustion-gas pathways; wherein the one or more fuel pathways fluidly communicate with the plurality of combustion-gas pathways through a plurality of pore-like openings in the plurality of combustion fins.
 11. The monolithic combustor body of claim 10, comprising: one or more fuel injectors monolithically integrated with a proximal portion of the combustor body and/or a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 12. The monolithic combustor body of claim 11, wherein the one or more fuel injectors are monolithically integrated with the plurality of heating walls and/or with a plurality of combustion fins circumferentially spaced about a perimeter of the combustion chamber, the plurality of combustion fins defining a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 13. The monolithic combustion body of claim 1, comprising: a plurality of burner gaps, respective ones of the plurality of burner gaps defined in respective ones of the plurality of heating walls, the second combustion zone at least partially coinciding with the plurality of burner gaps; wherein the plurality of burner gap comprises one or more of: an open space, a mesh, a three-dimensional lattice, or a porous medium.
 14. The monolithic combustor body of claim 1, comprising: a pilot burner configured to provide a pilot flame occupying the first combustion zone, wherein the pilot flame provides an ignition source for combustion in the second combustion zone.
 15. The monolithic combustor body of claim 1, comprising: a conditioning conduit body circumferentially surrounding at least a portion of the combustion chamber body, the conditioning conduit body and the combustion chamber body defining a conditioning conduit fluidly communicating with an upstream portion of the combustion chamber at a distal portion of the combustion chamber.
 16. The monolithic combustor body of claim 15, comprising: a downstream portion of the plurality of combustion-gas pathways fluidly communicating with a proximal portion of a conditioning conduit defined by the combustor body; and a distal portion of the conditioning conduit fluidly communicating with a distal portion of the combustion chamber.
 17. The monolithic combustor body of claim 15, wherein the conditioning conduit is configured to at least partially establish and/or sustain the vortex flow field.
 18. The monolithic combustor body of claim 15, wherein the combustion chamber and the conditioning conduit together provide a vortex combustion pattern comprising a bidirectional coaxial vortex flow field, the conditioning conduit defining a pathway for an outward portion of the bidirectional coaxial vortex flow field and the combustion chamber defining a pathway for an inward portion of the bidirectional coaxial vortex flow field.
 19. The monolithic combustor body of claim 1, wherein the plurality of combustion-gas pathways follow an annular or semiannular spiral trajectory relative to the combustion chamber and/or the longitudinal axis.
 20. The monolithic combustor body of claim 1, comprising: a vortex conditioner monolithically integrated with a proximal portion of the combustion chamber, the vortex conditioner having a conical or frustoconical shape projecting into the combustion chamber along the longitudinal axis.
 21. The monolithic combustor body of claim 20, comprising: one or more heat-capture pathways monolithically integrated with a proximal portion of the combustor body, the one or more heat-capture pathways fluidly communicating with the combustion chamber at a plurality of openings circumferentially surrounding the vortex conditioner and/or disposed about the vortex conditioner.
 22. A monolithic combustor body configured to provide multi-stage combustion, the combustor body comprising: a combustion chamber body disposed annularly about a longitudinal axis and defining a combustion chamber; a plurality of heating walls comprising a heat sink, the plurality of heating walls occupying a radially or concentrically outward position relative to the combustion chamber and defining a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber; and a vortex conditioner monolithically integrated with a proximal portion of the combustion chamber, the vortex conditioner having a conical or frustoconical shape projecting into the combustion chamber along the longitudinal axis; wherein during operation, the combustor body exhibits multi-stage combustion, the multi-stage combustion comprising: a first combustion zone occupying a distal or medial position of the combustion chamber relative to the longitudinal axis; and a second combustion zone occupying a proximal position relative to the first combustion zone, and a radially or concentrically outward position of the combustion chamber and/or a radially or concentrically inward position of the plurality of combustion-gas pathways.
 23. The monolithic combustor body of claim 22, comprising: one or more heat-capture pathways monolithically integrated with a proximal portion of the combustor body, the one or more heat-capture pathways fluidly communicating with the combustion chamber at a plurality of openings circumferentially surrounding the vortex conditioner and/or disposed about the vortex conditioner.
 24. A monolithic combustor body configured to provide multi-stage combustion, the combustor body comprising: a combustion chamber body disposed annularly about a longitudinal axis and defining a combustion chamber; a plurality of heating walls comprising a heat sink, the plurality of heating walls occupying a radially or concentrically outward position relative to the combustion chamber and defining a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber; and a plurality of combustion fins circumferentially spaced about a perimeter of the combustion chamber, the plurality of combustion fins defining a radially or concentrically inward portion of the plurality of combustion-gas pathways; wherein during operation, the combustor body exhibits multi-stage combustion, the multi-stage combustion comprising: a first combustion zone occupying a distal or medial position of the combustion chamber relative to the longitudinal axis; and a second combustion zone occupying a proximal position relative to the first combustion zone, and a radially or concentrically outward position relative to the longitudinal axis of the combustion chamber and/or a radially or concentrically inward position of the plurality of combustion-gas pathways defined by the plurality of heating walls.
 25. The monolithic combustor body of claim 24, wherein the plurality of combustion fins define a portion of respective ones of the plurality of heating walls.
 26. The monolithic combustor body of claim 24, wherein the second combustion zone occupies at least part of the radially or concentrically inward portion of the plurality of combustion-gas pathways defined by the plurality of combustion fins.
 27. The monolithic combustor body of claim 24, wherein the plurality of combustion fins and/or the plurality of heating walls are configured to support auto-ignition at the second combustion zone when heated by combustion at the first combustion zone.
 28. The monolithic combustor body of claim 24, wherein the second combustion zone occupies at least part of a proximal region of the combustion chamber.
 29. The monolithic combustor body of claim 24, wherein the heat sink comprises a plurality of working-fluid pathways, the plurality of working fluid pathways having a heat transfer relationship with the plurality of combustion-gas pathways.
 30. The monolithic combustor body of claim 29, wherein the plurality of heating walls comprise the plurality of working-fluid pathways monolithically formed within at least a portion of the plurality of heating walls.
 31. The monolithic combustor body of claim 24, comprising: one or more fuel pathways monolithically integrated with a proximal portion of the combustion chamber body and/or a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 32. The monolithic combustor body of claim 24, wherein the one or more fuel pathways fluidly communicate with the plurality of combustion-gas pathways through a plurality of pore-like openings in the plurality of combustion fins.
 33. The monolithic combustor body of claim 32, comprising: one or more fuel injectors monolithically integrated with a proximal portion of the combustor body and/or a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 34. The monolithic combustor body of claim 33, wherein the one or more fuel injectors are monolithically integrated with the plurality of heating walls and/or with a plurality of combustion fins circumferentially spaced about a perimeter of the combustion chamber, the plurality of combustion fins defining a radially or concentrically inward portion of the plurality of combustion-gas pathways.
 35. The monolithic combustion body of claim 24, comprising: a plurality of burner gaps, respective ones of the plurality of burner gaps defined in respective ones of the plurality of heating walls, the second combustion zone at least partially coinciding with the plurality of burner gaps; wherein the plurality of burner gap comprises one or more of: an open space, a mesh, a three-dimensional lattice, or a porous medium.
 36. The monolithic combustor body of claim 24, comprising: a pilot burner configured to provide a pilot flame occupying the first combustion zone, wherein the pilot flame provides an ignition source for combustion in the second combustion zone.
 37. The monolithic combustor body of claim 24, wherein during operation, the combustion chamber provides a vortex combustion pattern comprising a vortex flow field having a centripetal force that draws a combustion flame inward while propelling unburnt combustion gas outward, and wherein the first combustion zone occupies at least a portion of the vortex flow field.
 38. The monolithic combustor body of claim 24, comprising: a conditioning conduit body circumferentially surrounding at least a portion of the combustion chamber body, the conditioning conduit body and the combustion chamber body defining a conditioning conduit fluidly communicating with an upstream portion of the combustion chamber at a distal portion of the combustion chamber.
 39. The monolithic combustor body of claim 38, comprising: a downstream portion of the plurality of combustion-gas pathways fluidly communicating with a proximal portion of a conditioning conduit defined by the combustor body; and a distal portion of the conditioning conduit fluidly communicating with a distal portion of the combustion chamber.
 40. The monolithic combustor body of claim 38, wherein the combustion chamber and the conditioning conduit together provide a vortex combustion pattern comprising a bidirectional coaxial vortex flow field, the conditioning conduit defining a pathway for an outward portion of the bidirectional coaxial vortex flow field and the combustion chamber defining a pathway for an inward portion of the bidirectional coaxial vortex flow field.
 41. The monolithic combustor body of claim 24, wherein the plurality of combustion-gas pathways follow an annular or semiannular spiral trajectory relative to the combustion chamber and/or the longitudinal axis.
 42. The monolithic combustor body of claim 41, wherein during operation, the second combustion zone exhibits auto-ignition, wherein the first combustion zone exhibits a lean combustion environment prior to auto-ignition at the second combustion zone, and wherein upon auto-ignition at the second combustion zone, the first combustion zone transitions to a rich combustion environment and the second combustion zone thereafter exhibits a lean combustion environment.
 43. The monolithic combustor body of claim 24, comprising: a vortex conditioner monolithically integrated with a proximal portion of the combustion chamber, the vortex conditioner having a conical or frustoconical shape projecting into the combustion chamber along the longitudinal axis.
 44. The monolithic combustor body of claim 43, comprising: one or more heat-capture pathways monolithically integrated with a proximal portion of the combustor body, the one or more heat-capture pathways fluidly communicating with the combustion chamber at a plurality of openings circumferentially surrounding the vortex conditioner and/or disposed about the vortex conditioner.
 45. A monolithic combustor body configured to provide multi-stage combustion, the combustor body comprising: a combustion chamber body disposed annularly about a longitudinal axis and defining a combustion chamber; a heat exchanger having a plurality of heating walls comprising a heat sink, the plurality of heating walls occupying a radially or concentrically outward position relative to the combustion chamber and defining a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber; and a conditioning conduit body circumferentially surrounding at least a portion of the combustion chamber body, the conditioning conduit body and the combustion chamber body defining a conditioning conduit fluidly communicating with an upstream portion of the combustion chamber at a distal portion of the combustion chamber; wherein during operation, the combustion chamber and the conditioning conduit together provide a vortex combustion pattern comprising a bidirectional coaxial vortex flow field, the conditioning conduit defining a pathway for an outward portion of the bidirectional coaxial vortex flow field and the combustion chamber defining a pathway for an inward portion of the bidirectional coaxial vortex flow field, and wherein the bidirectional coaxial vortex flow field comprises a centripetal force within the combustion chamber that draws a combustion flame inward while propelling unburnt combustion gas outward; and wherein during operation, the combustor body exhibits multi-stage combustion, the multi-stage combustion comprising: a first combustion zone occupying a distal or medial position of the combustion chamber relative to the longitudinal axis, wherein the first combustion zone occupies at least a portion of the vortex flow field; and a second combustion zone occupying a proximal position relative to the first combustion zone, and a radially or concentrically outward position relative to the longitudinal axis of the combustion chamber and a radially or concentrically inward position of the plurality of combustion-gas pathways defined by the plurality of heating walls of the heat exchanger.
 46. The monolithic combustor body of claim 45, wherein during operation, the second combustion zone exhibits auto-ignition, wherein the first combustion zone exhibits a lean combustion environment prior to auto-ignition at the second combustion zone, and wherein upon auto-ignition at the second combustion zone, the first combustion zone transitions to a rich combustion environment and the second combustion zone thereafter exhibits a lean combustion environment. 